I am having trouble figuring out how to store the operator that the user inputs. I think my line 36 is what is causing my problem but not sure so what happens (I'm sure you can see from the code but I can't ;)) is I get to line 35 and put in the operation to use for the integers and hit enter nothing happens I then type in any 2 alphanumeric characters hit enter and nothing then 2 alphanumeric and enter then it spits out my answer. I know it's probably something so easy I am missing.
Also after I get that part working I would like to add a "do while" loop for the user to continue to use whichever operator that was choose until iValue1 !=0
Lastly, is the simplest way to prevent a user to divide by 0 using an "if" cin.fail? If so would that go with my first "if" statement?
*Edit: Line 35 = "cout << "Enter the operation you want to perform:"
#include <iostream>
using namespace std;
int main()
{
float iValue1, iValue2, iValue3;
char chOperator1 = '/'; //Initializing operators
char chOperator2 = '*';
char chOperator3 = '+';
char chOperator4 = '-';
//Get user inputs
cout << "Enter the first value as an integer: ";
cin >> iValue1;
cout << "Enter the Second value as an integer: ";
cin >> iValue2;
cout << "Enter the operation you want to perform: ";
cin >> chOperator1 >> chOperator2 >> chOperator3 >> chOperator4;
if( chOperator1 == '/')
{
iValue3 = iValue1 / iValue2;
}
else {
if(chOperator2 == '*')
iValue3 = iValue1 * iValue2;
(chOperator3 == '+');
iValue3 = iValue1 + iValue2;
(chOperator4 == '-');
iValue3 = iValue1 - iValue2;
}
cout << "The result is \n " << iValue3;
return 0;
}
I suggest you use an array or a std::vector for multiple operations:
char operations[4];
cout >> "Enter 4 operations: ";
for (unsigned int i = 0; i < 4; ++i)
{
cin >> operation[i];
}
for (unsigned int j = 0; j < 4; ++j)
{
const char opr = operation[j];
switch (j)
{
case '*':
cout << (iValue1 * iValue2) << "\n";
break;
case '/':
cout << (iValue1 / iValue2) << "\n";
break;
case '+':
cout << (iValue1 + iValue2) << "\n";
break;
case '-':
cout << (iValue1 - iValue2) << "\n";
break;
default:
cout << "Invalid operation, '" << oper << "'\n";
break;
}
}
Related
Hi I want to create a 2d growing dynamic array with use of char. The problem is that my function put all word in the same row. The dynamic allocation is not good but I don't know how to correct this.
void display(char** data, int length)
{
for (int i = 0; i < length; i++)
for (int j = 0; j < data[i][j] != '\0'; j++)
cout << data[i][j];
cout << endl;
}
void add(char** &data, int length, char* word)
{
if (length == 1)
{
data = new char* [length];
}
data[length-1] = new char[strlen(word)+1];
strcpy_s(*(data + length -1), strlen(word) + 1, word);
data[length - 1][strlen(word) + 1] = '\0';
}
int main()
{
char** data = NULL;
int choice = 0, length = 0; char name[80];
cout << "Enter your choice" << endl;
while (cin >> choice && choice != 3)
{
switch (choice)
{
case 0:
cout << "Enter name to add: " << endl;
cin.ignore(); cin.getline(name, 80);
length++;
add(data, length, name);
break;
}
cout << endl << "Enter your next choice: " << endl;
}
This is what is get
Enter your choice
0
Enter name to add:
jhon
jhon
Enter your next choice:
0
Enter name to add:
marc
jhonmarc
I'm pretty sure that instead of
if (length = 1)
you meant to write
if (length == 1)
In C++ = means assignment and == means equality.
Seems your code has other bugs though. You never grow the size of data. Do it the easy way and use std::vector<std::string>
#include <vector>
#include <string>
int main()
{
std::vector<std::string> data;
int choice = 0, length = 0; std::string name;
cout << "Enter your choice" << endl;
while (cin >> choice && choice != 3)
{
switch (choice)
{
case 0:
cout << "Enter name to add: " << endl;
cin.ignore(); getline(cin, name); // read name
data.push_back(name); // add name to data
break;
}
cout << endl << "Enter your next choice: " << endl;
}
Problem solved.
I'm new to C++. I have errors. But, i dont know how to fix it. Could anyone please help me? Thank you.
P - Print numbers
A - Add a number
M - Display mean of the numbers
S - Display the smallest number
L - Display the largest number
Q - Quit
Errors : expected unqualified id before return 0
error : expected ';' before {}
#include <iostream>
#include <vector>
using namespace std;
int main(){
char input {};
vector <double> numbers {};
int number{};
int sum{};
int min_number{};
int max_number{};
bool condition {true};
cout << "Enter a command" << endl;
cin >> input;
if(numbers.size() > 0){
while(condition){
if (input == 'P' || input == 'p'){
for(auto x: numbers)
cout << x << endl;
}
else if(input == 'A' || input == 'a'){
cout << "Enter a number";
cin >> number;
numbers.push_back(number);
}
else if(input == 'M' || input == 'm'){
for(auto x : numbers)
sum += x;
cout << sum / numbers.size() << endl;
}
else if(input =='S' || input == 's'){
for(size_t i {0}; i < numbers.size(); ++i)
if(numbers.at(i) < min_number)
min_number =numbers.at(i);
}
else if(input =='L' || input == 'l'){
for(size_t i {0}; i < numbers.size(); ++i)
if(numbers.at(i) > max_number)
max_number =numbers.at(i);
}
else if(input =='Q' || input == 'q'){
condition {false};
}
}
cout << "[] - list is empty, unable to calculate" << endl;
}
return 0;
}
In your section dealing with Q/q, the statement:
condition {false};
is not a valid form of assignment, you should instead use:
condition = false;
The braces are fine for initialisation, but that's not what you're trying to do on that line.
As an aside, this line:
if(numbers.size() > 0){
seems a little strange. Since you initialise the list to empty, the main loop will never start (because it's inside the if block) even though you have already asked the user for input.
That's a runtime error rather than a syntax error but you'll still need to fix it at some point.
I suspect that particular should should be done only as part of the calculation of the mean, so as to avoid dividing by zero.
I have written this for you. Since, you're a learner, I think that you should be practicing better things like STL functions and not using using namespace std; at top.
You may find some things new, but don't be frightened, just search them on some website like cppreference and see what that entity do and how to effectively use it.
There were many logical errors. #paxdiablo has mentioned them in his answer. I have removed every of them and this code works.
#include <algorithm>
#include <cctype>
#include <iostream>
#include <vector>
int main() {
std::vector<double> numbers;
while (true) {
char input;
std::cout << "Enter a command: ";
std::cin >> input;
switch (std::toupper(input)) {
case 'P':
if (numbers.empty())
std::cerr << "The list is empty!" << std::endl;
else {
for (auto &&i : numbers)
std::cout << i << ' ';
std::cout << std::endl;
}
break;
case 'A': {
int number;
std::cout << "Enter a number: ";
std::cin >> number;
numbers.push_back(number);
break;
}
case 'M':
if (numbers.empty())
std::cerr << "The list is empty! Cannot perform the operation!!";
else {
int sum = 0;
for (auto &&i : numbers)
sum += i;
std::cout << "Mean: " << (sum / numbers.size()) << std::endl;
}
break;
case 'S':
std::cout << "Smallest Number: " << *std::min_element(numbers.begin(), numbers.end()) << std::endl;
break;
case 'L':
std::cout << "Largest Number: " << *std::max_element(numbers.begin(), numbers.end()) << std::endl;
break;
case 'Q':
return 0;
default:
std::cerr << "Unrecognised Command!!" << std::endl;
}
}
return 0;
}
Basically, this program allows a user to enter a sentence and depending on the users selection, it will show the middle character of the sentence, display it uppercase or lowercase, or backwards. Simple program, but I am new to programming so that may be the problem. I would like to figure out how to use loops instead of a ton of if statements. When I try to make some loops it breaks certain parts of the code but I am sure that is because I don't properly understand them. If you have any criticism or any advice on the code, I'd be happy to hear it. Thanks in advance!
#include "stdafx.h"
#include <iostream>
#include <string>
using namespace std;
int main()
{
int sel;
string sent;
bool validinput;
int i;
int x;
int j;
int a;
cout << "Welcome to my program. Enter a sentence and select one of the options below.\n";
cout << "Enter -999 to exit the program." << endl;
cout << "============================================================================" << endl;
cout << endl;
cout << "1. Display the middle character if there is one." << endl;
cout << "2. Convert to uppercase." << endl;
cout << "3. Convert to lowercase." << endl;
cout << "4. Display backwards." << endl;
cout << "Enter a sentence: ";
getline (cin, sent);
cout << "Selection: ";
cin >> sel;
if (sel < 1 && sel > 4)
{
cout << "Invalid input. Try again. Selection: ";
cin >> sel;
validinput = false;
}
else (sel >= 1 && sel <= 4);
{
validinput = true;
}
if (validinput == true)
{
if (sel == 1)
{
j = sent.length() / 2;
cout << "The middle character is: " << sent.at(j) << endl;
}
if (sel == 2)
{
for (int i = 0; i < sent.length(); i++)
{
if (sent.at(i) >= 'a' && sent.at(i) <= 'z')
{
sent.at(i) = sent.at(i) - 'a' + 'A';
}
}
cout << "Uppercase: " << sent << endl;
}
if (sel == 3)
{
for (int x = 0; x < sent.length(); x++)
{
if (sent.at(x) >= 'A' && sent.at(x) <= 'Z')
{
sent.at(x) = sent.at(x) - 'A' + 'a';
}
}
cout << "Lowercase: " << sent << endl;
}
if (sel == 4)
{
for (a = sent.length() - 1; a >= 0; a--)
{
cout << sent.at(a);
}
}
}
system("pause");
return 0;
}
Personally I would use the switch selection statement. I roughly did this just to explain a bit on how it can make your code more friendly and understandable.
int sel;
bool validInput = false;
switch(sel)
{
case 1:
//display middle char if there's one
case 2:
//convert to uppercase
case 3:
//convert to lowercase
case 4:
//display backwards
validInput = true;
break;
default: //if number does not meat 1, 2, 3 or 4
validInput = false;
break;
}
As you may notice, for case 1, case 2, case 3 and case 4, there's a break just to say that if the number is between 1 to 4; validInput is true.
Reference: Switch Selection Statement
i suggest using a switch. It will organize your code better. From looking at your code you seem to have used for and if wisely. But I suggest the if statements checking for the input be replaced with switch.
I have the following code in a for loop. When it goes through for the first time, it runs great. However, when it gets run again, it stops just before the cin.ignore, and I have to hit the enter key before I can type my input. Any reason why that is? Thanks.
cin.ignore(100, '\n');
string input;
getline(cin, input);
EDIT:
Here is the entire part of the code:
Note that the vector restaurants has 16 strings in it. And the function ifOddNumberOfRestaurants is the following:
void ifOddNumberOfRestaurants(vector<string> restaurants){
cout << "To begin the tournament, please add one more restaurant to the list: ";
cin.ignore(1000, '\n');
string newRestaurant;
getline(cin, newRestaurant);
restaurants.push_back(newRestaurant);
}
The code with problems:
else if ( option == 5 ) {
int numberRestaurants = restaurants.size();
int evenOrOdd = numberRestaurants % 2;
if (evenOrOdd == 1){
ifOddNumberOfRestaurants(restaurants);
}
vector<string> battleRestaurants(restaurants);
int stop = 0;
while ( stop == 0 ){
double half = battleRestaurants.size()/2;
int option1 = 0;
int option2 = 1;
int match = 1;
for(int i = 0; i < half; i++){
cout << "Match " << match << "/" << half << " --- " << battleRestaurants[option1] << " *OR* " << battleRestaurants[option2] << "? ";
match++;
cout << "\nBEFORE IGNORE\n";
cin.ignore(100, '\n');
cout << "\nAFTER IGNORE\n";
string winner;
getline(cin, winner);
if ( winner == battleRestaurants[option1]){
battleRestaurants.erase(battleRestaurants.begin() + option2);
}
else if ( winner == battleRestaurants[option2]){
battleRestaurants.erase(battleRestaurants.begin() + option1);
}
option1++;
option2++;
cout << "Postion of i: " << i << "\nPosition of Option 1: " << option1 << "\nPosition of Option 2: " << option2 << "\n" << endl;
printRestaurants(battleRestaurants);
}
}
}
I Think your problem is that you have the cin.ignore(100, '\n'); When you do not need it remove that and your code should work ok. I tried just a little snippet of that part and it worked fine. EX: `vector restaurants;
int numberRestaurants = restaurants.size();
int evenOrOdd = numberRestaurants % 2;
for (int i = 0; i < 5; i++)
{
if (evenOrOdd == 1){
cout << "To begin the tournament, please add one more restaurant to the list: ";
//cin.ignore(100, '\n');
string newRestaurant;
getline(cin, newRestaurant);
restaurants.push_back(newRestaurant);
}
}
Remove the ignore thats why you have to push enter before it accepts anything else because it will ignore the first 100 chars or a new line whichever comes first.
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>