C++: Will Not Accept New C-String Input - c++

First off, thanks in advance for your help. This issue is driving me nuts.
I have a program that accepts a c-string, and then can count the number of vowels and consonants. This works without issue. However, I also need to include a function that allows the user to create a new string. The problem is, though, when the user selects "new string" from the menu, it just loops through the newString() method, without waiting for the user's input. It then creates a new, blank screen.
Here is the entire program. The newString() method is at the end.
#include <iostream>
using namespace std;
// function prototype
void printmenu(void);
int vowelCount(char *);
int consCount(char *);
int cons_and_vowelCount(char *);
void newString(char *, const int);
int main() {
const int LENGTH = 101;
char input_string[LENGTH]; //user defined string
char choice; //user menu choice
bool not_done = true; //loop control flag
// create the input_string object
cout << "Enter a string of no more than " << LENGTH-1 << " characters:\n";
cin.getline(input_string, LENGTH);
do {
printmenu();
cin >> choice;
switch(choice)
{
case 'a':
case 'A':
vowelCount(input_string);
break;
case 'b':
case 'B':
consCount(input_string);
break;
case 'c':
case 'C':
cons_and_vowelCount(input_string);
break;
case 'd':
case 'D':
newString(input_string, LENGTH);
break;
case 'e':
case 'E':
exit(0);
default:
cout << endl << "Error: '" << choice << "' is an invalid selection" << endl;
break;
} //close switch
} //close do
while (not_done);
return 0;
} // close main
/* Function printmenu()
* Input:
* none
* Process:
* Prints the menu of query choices
* Output:
* Prints the menu of query choices
*/
void printmenu(void)
{
cout << endl << endl;
cout << "A) Count the number of vowels in the string" << endl;
cout << "B) Count the number of consonants in the string" << endl;
cout << "C) Count both the vowels and consonants in the string" << endl;
cout << "D) Enter another string" << endl;
cout << "E) Exit the program" << endl;
cout << endl << "Enter your selection: ";
return;
}
int vowelCount(char *str) {
char vowels[11] = "aeiouAEIOU";
int vowel_count = 0;
for (int i = 0; i < strlen(str); i++) {
for (int j = 0; j < strlen(vowels); j++) {
if (str[i] == vowels[j]) {
vowel_count++;
}
}
}
cout << "String contains " << vowel_count << " vowels" << endl;
return vowel_count;
} // close vowelCount
int consCount(char *str) {
char cons[43] = "bcdfghjklmnpqrstvwxyzBCDFGHJKLMNPQRSTVWXYZ";
int cons_count = 0;
for (int i = 0; i < strlen(str); i ++) {
for (int j = 0; j < strlen(cons); j++) {
if (str[i] == cons[j]) {
cons_count++;
}
}
}
cout << "String contains " << cons_count << " consonants" << endl;
return cons_count;
} // close consCount
int cons_and_vowelCount(char *str) {
int cons = consCount(str);
int vowels = vowelCount(str);
int total = cons + vowels;
cout << "The string contains a total of " << total << " vowels and "
"consonants" << endl;
return total;
}
void newString(char *str, int len) {
cout << "Enter a string of no more than " << len-1 << " characters:\n";
cin.getline(str, len);
return;
}

The statement cin >> choice only consumes the character they type, not the carriage return that follows. Thus, the subsequent getline() call reads an empty line. One simple solution is to call getline() instead of cin >> choice and then use the first character as the choice.
BTW, the while (not done) should immediately follow the do { … }, and the return 0 is redundant. Also, you should call newString at the start of the program instead of repeating its contents.

cin >> choice leaves a newline in the input stream.. which cause the next getline() to consume it and return. There are many ways.. one way is to use cin.ignore() right after cin >> choice.

The cin >> choice only consumes one character from the stream (as already mentioned). You should add
cin.ignore(std::numeric_limits<std::streamsize>::max(),'\n');
right after cin>>choice to ignore all the characters that come into the stream after reading the choice.
p.s. #include <limits>

Related

Check letters against the word of an arbitrary size in a Hangman game

Currently I am working on a hangman game, I had previously coded it to only work for a 5 letter word, but now would like to make it handle any length of word, how could I change this code to make it work how I want it to?
#include "stdafx.h"
#include <iostream>
#include <string>
#include <stdlib.h>
#include <cstdlib>
using namespace std;
int main()
{
string word;
int tries;
string guess;
string wordguess;
string output;
cout << "Enter a word for player two to guess: ";
cin >> word;
system("CLS");
cout.flush();
cout << "Guess the word!" << endl;
for (int i = 0; i < word.length(); i++)
{
cout << "_ ";
}
cout << "Enter a letter: ";
cin >> guess;
for (int tries = 5; tries > 0; tries--)
{
if (guess[0] == word[0]) {
output[0] = word[0];
cout << "You guessed the first letter! Good job!" << endl;
}
if (guess[0] == word[1]) {
output[2] = word[1];
cout << "You guessed the second letter! Good job!" << endl;
}
if (guess[0] == word[2]) {
output[4] = word[2];
cout << "You guessed the third letter! Good job!" << endl;
}
if (guess[0] == word[3]) {
output[6] = word[3];
cout << "You guessed the fourth letter! Good job!" << endl;
}
if (guess[0] == word[4]) {
output[8] = word[4];
cout << "You guessed the fifth letter! Good job!" << endl;
}
cout << output << endl;
cout << "You have " << tries << " tries left. Take a guess at the word: " << endl;
cin >> wordguess;
if (wordguess == word)
{
cout << "Congratulations, you guessed the word correctly!" << endl;
break;
}
}
system("pause");
return 0;
}
As you can tell I was checking each position from 0 to 4 (first through fifth letter). I know there are plenty of ways that I could have coded this better but as you can guess, I am new to coding and this is the way I thought of it. Please note this is still a work in progress so it is not fully complete. Any help would be great!
When designing an algorithm, think of how you would do this by hand, without a computer. Then let the code do the same.
If you were checking your friend's guess against a word written on sand, you would probably go about it like this:
go through the written pattern character by character, pronouncing your word in memory
for each letter, check if it is equal to the guess
if it is
replace the placeholder with it
memorize that your friend guessed right.
Also note if there are any placeholders left
if there aren't, your friend wins
finally, if your friend didn't guess right, score them a penalty point and check if they lose
Now, all that leaves is to put this down in C++. The language provides all sorts of entities - let's check which ones fit ours needs the best:
the word and the current pattern - strings of a fixed size
bits to memorize:
whether the current guess is right - bool
placeholders left - int
penalty points (or, equivalently, attempts left) - int
parts of the algorithm:
looping over a string - for loop of one of a few kinds
we need to replace the character in the pattern at the same index as the guessed letter in the word. So, we need to have the index when looping. Thus the flavor with the index variable, for(std::string::size_type i = 0; i < str.size(); ++i) probably fits the best.
// Example program
#include <iostream>
#include <string>
using namespace std;
class my_game
{
private:
string congrats_array[15] = {"first", "second", "third", "fourth", "fifth", "sixth", "seventh", "eighth", "nineth", "tenth", "eleventh", "twelfth", "thirteenth", "fourteenth", "fifteenth"};
string word_to_guess;
int tries_left;
int word_length;
int letters_guessed_count;
string guessed_letters;
void check_letter(char letter);
void print_current_word_state();
public:
my_game();
void begin_the_game();
void play_the_game();
};
my_game::my_game()
{
}
void my_game::begin_the_game()
{
cout << "Enter a word for player to guess: " << endl;
cin >> word_to_guess;
system("CLS");
cout.flush();
cout << "Enter the tries amount!\n" << endl;
cin >> tries_left;
word_length = word_to_guess.size();
guessed_letters = "_";
letters_guessed_count = 0;
for(int i = 0; i < word_length - 1; i++){
guessed_letters += "_";
}
}
void my_game::play_the_game()
{
cout << "Guess the word!" << endl;
char letter;
for(int i = 0; i < tries_left; i++)
{
cout << guessed_letters << endl;
cout << "Enter a letter: " << endl;
cin >> letter;
check_letter(letter);
if(letters_guessed_count == word_length){
cout << "Congrats! You won!" << endl;
return;
}
}
cout << "You lose" << endl;
}
void my_game::check_letter(char letter)
{
for(int i = 0; i < word_length; i++)
{
if(word_to_guess[i] == letter && guessed_letters[i] != letter)
{
guessed_letters[i] = letter;
letters_guessed_count++;
cout << "You guessed the" << congrats_array[i] <<"letter! Good job!" << endl;
}
}
}
int main()
{
my_game game;
game.begin_the_game();
game.play_the_game();
}
So, in short what you need to do this with words of any arbitrary length is to use string's .substr() function and the stringstream library's .str() and << and >> operators. This version of your code uses a function that inserts a correctly guessed character at the appropriate indexed location. This will gradually replace the "_________" with letters at the correct places. This is much easier to do in Java, but stringstream is a good library I would highly recommend getting familiar with it. I'll leave the problem of how to handle multiple instances of a guessed character up to you (ie 'i' in "bibliography")
#include <string>
using std::string;
#include <sstream>
using std::stringstream;
#include <iostream>
using std::cout;
using std::cin;
using std::endl;
string newString(string, int, string);
int main()
{
string word;
string guess;
int tries;
string output;
string input;
cout << "Enter word for player 2 to guess: ";
cin >> word;
stringstream ss;
//---------- fills the stream with "_"s matching the length of word
for(int i = 0; i < word.length(); i++)
ss << "_";
//----------- assigns the initial value of "___..." to output
ss >> output;
//----------- sets up the loop
tries = 5;
bool found = false;
for(int i = 0; i < 5; i++)
{
cout << "\nTry " << i << " of 5: Enter a letter or guess the word: ";
cin >> input;
if(input == word)
{
cout << "Congratulations, you guessed the word correctly!" << endl;
break;
}
//------------------ else, proceed with replacing letters
if(word.find(input) != std::string::npos)
{
size_t position = word.find(input); // finds index of first instance of the guessed letter
cout << "You guessed the " << position+1 << " letter! Good job!" << endl; // since strings start at index 0, position+1
//------- replaces appropriate "_" with the guessed letter
output = newString(input, position, output);
cout << "\n" << output;
// Around here you'll want to set up a way to deal with multiple instances
// of the same letter
}
else
cout << "Incorrect guess" << endl;
}
return 0;
}
//---------------------------------------------------
string newString(string guess, int index, string word)
{
string NewString;
stringstream temp;
//---------- hack up the string into sections before and after the index
string before = word.substr(0, index);
string after = word.substr(index+1, word.length() - index+1);
//---------------- populates the new stringstream and assigns it to the result
temp << before << guess << after;
NewString = temp.str();
return NewString;
}

Extra string outputs if user input is more than one word

This is my first time asking a question on here, so be gentle lol. I wrote up some code for an assignment designed to take information from a (library.txt datatbase) file, store it in arrays, then access/search those arrays by title/author then output that information for the user based on what the user enters.
The issue I am having is, whenever the user enters in a search term longer than one word, the output of "Enter Q to (Q)uit, Search (A)uthor, Search (T)itle, (S)how All: " is repeated several times before closing.
I am just looking to make this worthy of my professor lol. Please help me.
#include <iostream>
#include <fstream>
#include <string>
#include <iomanip>
using namespace std;
struct Book
{
string title;
string author;
};
int loadData(string pathname);
char switchoutput();
void showAll(int count);
int showBooksByAuthor(int count, string name);
int showBooksByTitle(int count, string title);
int FindAuthor(int count, string userinput);
int FindTitle(int count, string userinput);
void ConvertStringToLowerCase(const string orig, string& lwr); //I found this program useful to convert any given string to lowercase, regardless of user input
const int ARRAY_SIZE = 1000;
Book books[ARRAY_SIZE];
int main()
{
string pathname;
string name;
string booktitle;
int count = 0;
int counta = 0;
int countt = 0;
char input = 0;
cout << "Welcome to Jacob's Library Database." << endl;
cout << "Please enter the name of the backup file: " ;
cin >> pathname;
count = loadData(pathname);
cout << count << " records found in the database." << endl;
while (toupper(input != 'Q'))
{
input = switchoutput(); // function call for switchoutput function
switch (input)
{
case 'A':
cout << "Author's Name: ";
cin >> name;
counta = showBooksByAuthor(count, name);
cout << counta << " records found." << endl;
break;
case 'T':
cout << "Book Title: ";
cin >> booktitle;
countt = showBooksByTitle(count, booktitle);
cout << countt << " records found." << endl;
break;
case 'S':
showAll(count);
break;
case 'Q':
break;
}
}
//Pause and exit
cout << endl << "Press 'ENTER' to quit";
getchar();
getchar();
return 0;
}
int loadData(string pathname) //loading data into the array of structs
{
ifstream inFile;
inFile.open(pathname);
if (!inFile) {
cout << "Error, could not read into file. Please re-compile." << endl;
system("PAUSE");
exit(1); //if not in file, exit;
}
int i = 0;
while (!inFile.eof()) {
getline(inFile, books[i].title);
getline(inFile, books[i].author);
i++;
}
return i;
}
char switchoutput() //seperate output function to get my characteroutput constantly resetting and returning the uppercase version for my switch
{
char input;
cout << "Enter Q to (Q)uit, Search (A)uthor, Search (T)itle, (S)how All: ";
cin >> input;
return toupper(input);
}
int showBooksByAuthor(int count, string name)
{
int authorcount = 0;
authorcount = FindAuthor(count, name);
return authorcount;
}
int showBooksByTitle(int count, string title)
{
int titlecount = 0;
titlecount = FindTitle(count, title);
return titlecount;
}
void showAll(int count)
{
for (int i = 0; i < count; i++)
{
cout << books[i].title << " (" << books[i].author << ")" << endl;
}
}
int FindAuthor(int count, string userinput)
{
int authorcount = 0;
string stringlower, arraylower;
int num;
// called upon function to lowercase any of the user inputs
ConvertStringToLowerCase(userinput, stringlower);
for (int i = 0; i < count; ++i) //this function's count determines at which locations to output the author and names (an argument from books by author)
{
// called upon function to lowercase any of the stored authors'
ConvertStringToLowerCase(books[i].author, arraylower);
num = arraylower.find(stringlower); // searches string for userinput (in the lowered array) and stores its value
if (num > -1) // you can never get a -1 input value from an array, thus this loop continues until execution
{
cout << books[i].title << " (" << books[i].author << ")" << endl; //cout book title and book author
authorcount++; //count
}
}
return authorcount;
}
int FindTitle(int count, string userinput) //same as previous but for titles
{
int titlecount = 0;
string stringlower, arraylower;
int num;
ConvertStringToLowerCase(userinput, stringlower);
for (int i = 0; i < count; ++i)
{
ConvertStringToLowerCase(books[i].title, arraylower);
num = arraylower.find(stringlower);
if (num > -1)
{
cout << books[i].title << " (" << books[i].author << ")" << endl;
titlecount++; //count
}
}
return titlecount;
}
void ConvertStringToLowerCase(const string orig, string& lwr) // I found this from another classmate during tutoring, I thought to be useful.
{
lwr = orig;
for (int j = 0; j < orig.length(); ++j) //when called upon in my find functions, it takes the string and convers the string into an array of lowercase letters
{
lwr[j] = tolower(orig.at(j));
}
}

problems with conditional statement based off sizeof c++

I am new to c++ and and am working on a program that has is a simple dvd rental program. I am having issues with case 3 & 4 specifically. Maybe I am misunderstanding the purpose behind sizeof. What I am trying to have it do is tell if the char array is empty and if it is allow the user to check it out by putting their name in and if it is not available give them a response saying that it is not available. case 4 should do the opposite and allow them to check it in. Any suggestions would be greatly appreciated.
#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <string>
#include <limits>
using namespace std;
const int arrSize = 5;
struct dvdStruct //distance struct
{
int id;
char title[51] = { 0 };
char rating[5] = { 0 };
double price;
char borrower[51] = { 0 };
} dvd;
dvdStruct dvds[arrSize] = {};
int userSelection; //intput variable for main menu selection
int borrowId (0);
int borrowIdReturn(0);
//void initalize();
int main() {
int size(0);
dvds[0].id = 1;
dvds[1].id = 2;
dvds[2].id = 3;
dvds[3].id = 4;
dvds[4].id = 5;
strcpy(dvds[0].title, "Fast 1");
strcpy(dvds[1].title, "Fast 2");
strcpy(dvds[2].title, "Fast 3");
strcpy(dvds[3].title, "Fast 4");
strcpy(dvds[4].title, "Fast 5");
strcpy(dvds[0].rating, "PG - 13");
strcpy(dvds[1].rating, "PG - 13");
strcpy(dvds[2].rating, "PG - 13");
strcpy(dvds[3].rating, "PG - 13");
strcpy(dvds[4].rating, "PG - 13");
dvds[0].price = '19.1';
dvds[1].price = '19.2';
dvds[2].price = '19.3';
dvds[3].price = '19.4';
dvds[4].price = '19.5';
strcpy(dvds[0].borrower, "");
cout << strlen(dvds[0].borrower) << endl;
strcpy(dvds[1].borrower, "\0");
strcpy(dvds[2].borrower, "\0");
strcpy(dvds[3].borrower, "\0");
strcpy(dvds[4].borrower, "\0");
do {
cout << "1.Display All DVD’s" << endl << "2.Display DVD Detail" << endl << "3.Check Out a DVD" << endl << "4.Check In a DVD" << endl << "5.Exit" << endl;
cin >> userSelection; //Input from the user.
switch (userSelection)
{
case 1:
for (int i = 0; i < arrSize; i++)
{
std::cout << dvds[i].title << "' " << dvds[i].rating << " " << dvds[i].borrower << endl;
}
system("pause");
system("CLS");
break;
case 2:
int dvdNum;
cout << "Enter a DVD number:";
cin >> dvdNum;
std::cout << dvds[dvdNum - 1].title << "' " << dvds[dvdNum - 1].rating << endl;
system("pause");
system("CLS");
break;
case 3:
cout << "Enter and id:";
cin >> borrowId;
if (strlen(dvds[borrowId-1].borrower) == 0)
{
cout << "Enter your name: ";
cin >> dvds[borrowId-1].borrower;
}
else
{
cout << "This dvd is not available" << endl;
}
system("pause");
system("CLS");
break;
case 4:
cout << "Enter and id:";
cin >> borrowIdReturn;
if (strlen(dvds[borrowIdReturn - 1].borrower) == 0)
{
cout << "This dvd is available" << endl;
}
else
{
cout << "Your DVD has been returned " << endl;
strcpy(dvds[borrowIdReturn - 1].borrower, "\0");
}
system("pause");
system("CLS");
break;
case 5:
return 0;
break;
}
} while (userSelection == 1 || userSelection == 2 || userSelection == 3 || userSelection == 4);
}
sizeof() gives you the size of an object. The size of the object is always the same, no matter what's in the object. In fact, sizeof() is calculated at compile time, and its value could not be affected, in any way, by whatever happens at runtime.
C++ code should use std::string, instead of char arrays, in most cases. std::string's empty() method indicates whether the string is empty.
If you still insist on working with C-style char arrays, and C-style '\0' terminated strings, use the C strlen() function to check if the character array contains nothing but a leading '\0', indicating an empty string.

Why can't I print out my string array c++?

I have written this code and I am supposed to read in a txt file and read every other line in the txt file to the string array bookTitle[ARRAY_SIZE] and the other every other line to bookAuthor[ARRAY_SIZE]. Here is my code:
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
const int ARRAY_SIZE = 1000;
string bookTitle [ARRAY_SIZE];
string bookAuthor [ARRAY_SIZE];
int loadData(string pathname);
void showAll(int count);
//int showBooksByAuthor (int count, string name);
//int showBooksByTitle (int count, string title);
int main ()
{
int number, numOfBooks;
char reply;
string bookTitles, authorName, backupFile;
cout << "Welcome to Brigham's library database." << endl;
cout << "Please enter the name of the backup file:";
cin >> backupFile;
numOfBooks = loadData (backupFile);
if (numOfBooks == -1) {
cout << endl;
} else {
cout << numOfBooks << " books loaded successfully." << endl;
}
cout << "Enter Q to (Q)uit, Search (A)uthor, Search (T)itle, (S)how All:";
cin >> reply;
do {
switch (reply) {
case 'a':
case 'A':
cout << "Author's name: ";
cin >> authorName;
showBooksByAuthor (numOfBooks, authorName);
cout << endl;
break;
case 'q':
case 'Q':
cout << endl;
break;
case 's':
case 'S':
showAll(numOfBooks);
break;
case 't':
case 'T':
cout << "Book title: ";
cin >> bookTitles;
showBooksByTitle(numOfBooks, bookTitles);
cout << endl;
break;
default:
cout << "Invalid input" << endl;
break;
}
} while (reply != 'q' && reply != 'Q');
while (1==1) {
cin >> number;
cout << bookTitle[number] << endl;
cout << bookAuthor[number] << endl;
}
}
int loadData (string pathname){
int count = 0, noCount = -1;
ifstream inputFile;
string firstLine, secondLine;
inputFile.open(pathname.c_str());
if (!inputFile.is_open()) { //If the file does not open then print error message
cout << "Unable to open input file." << endl;
return noCount;
}
for (int i = 0; i <= ARRAY_SIZE; i++) {
while (!inputFile.eof()) {
getline(inputFile, firstLine);
bookTitle[i] = firstLine;
getline(inputFile, secondLine);
bookAuthor[i] = secondLine;
cout << bookTitle[i] << endl;
cout << bookAuthor[i] << endl;
count++;
}
}
return count;
}
void showAll (int count) {
for (int j = 0; j <= count; j++) {
cout << bookTitle[j] << endl;
cout << bookAuthor[j] << endl;
}
}
So I have the loadData function which I am pretty sure is my problem. When I have it print out each string[ith position] while running the loadData function it prints out each title and author just as it appears in the txt file. But then when I run the void showAll function which is supposed to be able to print the entire txt doc to the screen it doesn't work. Also just I checked to see if the strings were actually stored in memory and they were not. (After my do while loop I have a while loop that accepts input of type int and then prints the string array of the [input position]. This prints nothing. So what do I have to do to actually store each line to a different position in the string array(s)? Feel free to correct my code but it isn't pretty yet considering I still have two functions that I haven't done anything too. (Commented out).
You main problem is that you try to read you data using two loops rather than just one! You want read until either input fails or the array is filled, i.e., something like this:
for (int i = 0;
i < ARRAY_SIZE
&& std::getline(inputFile, bookTitle[i])
&& std::getline(inputFile, bookAuthor[i]); ++i) {
}
The problem with the original code is that it never changes the index i and always stores values into the cell with index 0. Since the input isn't checked after it is being read, the last loop iteration fails to read something and overwrites any earlier stored value with an empty value. Once reading of the stream fails the outer loop iterates over all indices but doesn't do anything as the check to the inner loop is always false.

How do I permenantly delete a row of arrays and shift a row of arrays upwards?

I've been assigned by school to create an application that contains a book list with 20 different books in it and build a menu with following options:
(a) List – Display the list in tabular format. Each display should contain an appropriate heading and column captions;
(b) Search – Search for a book record in the list using the ISBN and print the full record for the book;
(c) Delete – Delete an existing book record from the list;
(d) Exit – Stop the program.
Here is the sample of my program:
#include <iostream>
#include <iomanip>
#include <fstream>
#include <cstring>
#include <cctype>
using namespace std;
typedef struct
{
char code[50];
char author[50];
char name[50];
char edition[50];
char publish[50];
char price[50];
} BOOK_LIST;
void list (BOOK_LIST book[], int rows);
void showBook (BOOK_LIST book[], int rows);
void updateRecord (BOOK_LIST book[], int rows);
void advancedSearch (BOOK_LIST book[], int rows);
int deleteBook (BOOK_LIST book[], int rows);
int searchBook(BOOK_LIST book[], int rows);
int main()
{
ifstream inFile("list.txt");
if(!inFile)
cout << "Error opening input file\n";
else
{
BOOK_LIST books[50];
int index = -1, choice;
inFile.getline(books[++index].code, 50);
while(inFile)
{
if(inFile.peek() == '\n')
inFile.ignore(256, '\n');
inFile.getline(books[index].author, 50);
inFile.getline(books[index].name, 50);
inFile.getline(books[index].edition, 50);
inFile.getline(books[index].publish, 50);
inFile >> books[index].price;
// read next number
inFile >> books[++index].code;
}
inFile.close();
// menu starts
do
{
cout << "Do you want to:\n";
cout << "1. List all books\n";
cout << "2. Get details about a book\n";
cout << "3. Delete a book from the list\n";
cout << "4. Exit\n";
cout << "5. Advanced Search\n";
cout << "Enter choice: ";
cin >> choice;
switch (choice)
{
case 1 : list(books, index);
break;
case 2 : showBook(books, index);
break;
case 3 : updateRecord(books, index);
break;
case 5 : advancedSearch(books, index);
case 4 : break;
default: cout << "Invalid choice\n";
}
} while (choice != 4);
ofstream outFile("list.txt");
if(!outFile)
cout << "Error opening output file, records are not updated.\n";
else
{
for (int i = 0; i < index; i++)
{
outFile << books[i].code << endl;
outFile << books[i].author << endl;
outFile << books[i].name << endl;
outFile << books[i].edition << endl;
outFile << books[i].publish << endl;
outFile << books[i].price << endl;
}
outFile.close();
}
}
return 0;
}
void list(BOOK_LIST book[], int rows)
{
cout << fixed << setprecision(2);
cout << "ISBN\t Author BookName Edition\tPublisher\t Price\n";
for (int i = 0; i < rows; i++)
cout << book[i].code << "\t" << book[i].author << "\t"
<< book[i].name << "\t" << book[i].edition << "\t"
<< book[i].publish << "\t"
<< " " << book[i].price << endl;
return;
}
int searchBook(BOOK_LIST book[], int rows)
{
int i = 0;
bool found = false;
char code[50];
cout << "Enter an ISBN code of a book to search: ";
fflush(stdin);
cin.getline(code, 50);
while (i < rows && !found)
{
if (strcmp(code, book[i].code) == 0)
found = true;
else
i++;
}
if (found)
return i;
else
return -1;
}
void showBook(BOOK_LIST book[], int rows)
{
int pos = searchBook(book, rows);
if (pos != -1)
{
cout << "Author is " << book[pos].author << endl;
cout << "Book name is "<< book[pos].name << endl;
cout << book[pos].edition << " Edition" << endl;
cout << "The publisher of this book is " << book[pos].publish << endl;
cout << "Current price is " << book[pos].price << endl;
}
else
cout << "Product not found\n";
return;
}
void updateRecord(BOOK_LIST book[], int rows)
{
int pos = deleteBook(book, rows);
char code [50];
int i,j = 0;
for(i = 0; i < rows ; i++)
{
if(strcmp(code, book[i].code))
{
strcpy(book[j].code , book[i].code);
strcpy(book[j].author, book[i].author);
strcpy(book[j].name, book[i].name);
strcpy(book[j].edition, book[i].edition);
strcpy(book[j].publish, book[i].publish);
strcpy(book[j].price, book[i].price);
j++;
}//if
else
{
i++;
strcpy(book[j].code, book[i].code);
strcpy(book[j].author, book[i].author);
strcpy(book[j].name, book[i].name);
strcpy(book[j].edition, book[i].edition);
strcpy(book[j].publish, book[i].publish);
strcpy(book[j].price, book[i].price);
j++;
}//else
}//for
return;
}
int deleteBook (BOOK_LIST book[], int rows)
{
int i = 0;
bool found = false;
char code[50];
cout << "Enter an ISBN code of a book to delete: ";
fflush(stdin);
cin.getline(code, 50);
while (i < rows && !found)
{
if (strcmp(code, book[i].code) == 0)
found = true;
else
i++;
}
if (found)
return i;
else
return -1;
}
void advancedSearch (BOOK_LIST book[], int rows)
{
char advanced[50];
cout << "Please enter either the author's name or the book name to search: ";
fflush(stdin);
cin.getline(advanced, 50);
for(int i = 0; i < rows; i++)
{
if(strstr(book[i].author, advanced) || strstr(book[i].name, advanced))
{
cout << "ISBN is " << book[i].code << endl;
cout << "Author is " << book[i].author << endl;
cout << "Book name is " << book[i].name << endl;
cout << book[i].edition << " Edition" << endl;
cout << "Publisher is " << book[i].publish << endl;
cout << "Current price is " << book[i].price << endl;
}
}
return ;
}
The problem starts here:
When I want to permanently delete a whole row of book record. But the book record is still there after deleting.
First, this is my menu, then I press 1 to check the list for the IBSN. Then, I press 3 to proceed to the deleting part. At that time, I choose TheHost to delete. After the deleting, to ensure that I have deleted the chosen book, so I press 1 to check the list again, but unfortunately the book is still there:
If I am able to delete a book record, and how do I delete a record permanently? And after deleting a record, how do I move the remaining records upwards, so that it won't leave any empty row there?
The function for the deleting:
void updateRecord(BOOK_LIST book[], int rows)
{
int pos = deleteBook(book, rows);
char code [50];
int i,j = 0;
for(i = 0; i < rows ; i++)
{
if(strcmp(code, book[i].code))
{
strcpy(book[j].code , book[i].code);
strcpy(book[j].author, book[i].author);
strcpy(book[j].name, book[i].name);
strcpy(book[j].edition, book[i].edition);
strcpy(book[j].publish, book[i].publish);
strcpy(book[j].price, book[i].price);
j++;
}//if
else
{
i++;
strcpy(book[j].code, book[i].code);
strcpy(book[j].author, book[i].author);
strcpy(book[j].name, book[i].name);
strcpy(book[j].edition, book[i].edition);
strcpy(book[j].publish, book[i].publish);
strcpy(book[j].price, book[i].price);
j++;
}//else
}//for
return;
}
The Text file that I used in this program a.k.a the BOOK_LIST
I see (at least) two problems with your code around deleting a book.
in update_record you're using a char code[50] which is being used to compare with strcmp later on but is not initialized.
when you delete a book you should update your index which becomes rows in the update_record method. However index is passed to rows by value which means that even if you try running --rows; in update_record it won't decrement index. You'll need to pass it by reference for it to update index.
On a side note, I agree with comments regarding fixing your code to use vectors/maps & strings instead of simple arrays and char*.
But since you mentioned it was a school task I would guess you haven't reached that sort of material yet.
Good Luck.
The assignment most probably expects you to use std::list template rather than the classical C array. Insertion and deletion is natural for lists.
An alternative would be to use std:map using the ISBN as a key. ISBN is supposed to be globally unique.
Just to expand on my comment, here is one way to remove an element from an array.
Suppose we have an array of char called X, containing {'a', 'b', 'c', 'd', 'e', 'f'}, and we want to get rid of 'c'.
If we want to maintain the order of the remaining elements, then what we're aiming for is {'a', 'b', 'd', 'e', 'f'}. So we copy the 'd' into the 'c' place, the 'e' into the old 'd' place, and so on:
a b c d e f
a b d d e f
a b d e e f
a b d e f f
We can do this with code like
for(int k=2; k<5; ++k)
X[k] = X[k+1];
And what happens to that extra 'f' at the end? We could write some placeholder into that unwanted space, and then watch out for that placeholder for the rest of the run. Or, we could just stop using that space, and say that from now on we're considering an array of length 5. That extra 'f' will still be there, but for now we don't care about what exists past the end of our array.
(If we don't care about the order of the remaining elements, then we can make this a lot simpler.)
Remember, it's always easier to develop new functionality in isolation.
Once you have this working, you can apply it in your code and get a passing grade, but if you really want to learn something useful you should write a Book class.