I have been trying to parse through a text file in c++ to read the numbers that are contained within the file. The number of integers on each line and the number of lines is not know. When all the integers are read they will save that integer followed by a ',' and the running total of that line. This will then be outputted to a file chosen by the user. The code I have written is as follows:
#include <iostream>
#include <string>
#include <fstream>
using namespace std;
int main()
{
int i=0,b = 0,num = 100;
int *s1;
string myfilename, mystring, filename;
cout << "Enter the name of the file to open:" << endl;
cin >> myfilename;
cout << "Enter the name of the output file" << endl;
cin >> filename;
ifstream inFile;
ofstream outFile("C:\\Users\\Aidan Howie\\Documents\\University\\Second Year\\C++\\" + filename + ".txt");
inFile.open("C:\\Users\\Aidan Howie\\Documents\\University\\Second Year\\C++\\" + myfilename + ".txt");
if (!inFile)
{
cout << "Cannot open file" << endl;
return -1;
}
while (!inFile.eof())
{
s1 = new int[num];
for (i = 0; i < s1; i++)
{
cout << i << "," << (i + b) / s1;
b = i+b;
cout << endl;
}
}
inFile.close();
system("PAUSE");
}
However receive the error:
error C2446: '<' : no conversion from 'int *' to 'int'
Can anyone explain how to fix this and whether there is an easier way for me to read the unknown integers on the file
s1 is a pointer to an int, while i is an int. So essentially what you're doing is checking if 6 < 0x55ddab.
The right way to do it is: i < *s1
Also, don't forget to delete s1 before your while loop repeats.
Also, I'm just going to put a note that what you're doing makes no sense, nonetheless, using i < *s1 will fix your error.
s1 is an array of ints, which means that when you use the name s1 without an index, it is a pointer. Therefore, your comparison of i < s1 is asking if i is less than the address of s1, and that's not a valid comparison. Your line of code should look like this:
for (i = 0; i < num; i++)
Also, inFile.eof() isn't doing what you think it is. The only way you're going to get an EOF on inFile is if the user types ctrl+D. You should have the user enter some sentinel value to signal the end of input; for example, 0 or -1 or some other otherwise invalid value.
Related
Write and test a program that prompts the user to input a file name and a string to test for. Search the file for every occurrence of the specified string – when the string is found, display the line that contains it. When all occurrences of the string have been found display the number of times the string appeared in the file. Hint: You may use string member function find().
Here's my code, as I stated it works with some sentences but not all, it doesn't seem to have anything to do with the length either as if I repeat a line I know works, it won't run into any errors, can someone explain?
#include <fstream>
#include <iostream>
#include <sstream>
#include <string>
#include <vector>
#include <cctype>
using namespace std;
void find_common_words(string, int);
vector<string> words;
int main(){
vector<string> line;
string input;
char filename[50];
ifstream inputFile;
cout << "Enter File Name:" << endl;
cin.getline(filename, 50);
inputFile.open(filename);
//TESTING IF FILE IS OPEN
if (!inputFile.is_open()){
cout << "File Wasn't Opened!" << endl;
return 0;
}
while (getline(inputFile, input)){
line.push_back(input);
}
int size_of_array = static_cast<int>(line.size());
for (int i = 0; i < size_of_array; i++){
istringstream iss(line[i]);
int word_number = 0;
do {
string word;
iss >> word;
words.push_back(word);
word_number++;
} while (iss);
}
string commonword;
cout << "Enter a word to search for (without punctuation)" << endl;
cin >> commonword;
int size_of_array2 = static_cast<int>(words.size());
find_common_words(commonword, size_of_array2);
return 0;
}
void find_common_words(string search, int sizeofarray2) {
//CONVERSION TO STRING WITHOUT PUNCTUATION
for (int i = 0; i < sizeofarray2; i++){
string temp_string = words[i];
for (int j = 0, len = temp_string.size(); j < len; j++){
if (ispunct(temp_string[j])){
temp_string.erase(j--, 1);
len = temp_string.size();
}
}
words[i] = temp_string;
}
//SEARCHING FOR SAME WORDS
int line_number = 1;
int words_found = 0;
for (int i = 0; i < sizeofarray2; i++){
if (search == words[i]){
cout << search << " Was found on line " << line_number << endl;
words_found++;
}
if (words[i].length() == 0){
line_number++;
}
}
cout << line_number - 1 << " lines checked, " << words_found << " matches " << endl;
}
Heres my input file (randomly generated):
It's a very big deal.
Carl won the spelling bee and got a trophy!
Why is your cat so big?
Do you have a big bowl I can borrow?
It's a big company.
Penguins live in the Antarctica.
Don’t be silly, you're going to the game!
What are you talking about?
He threw up in the trash can!
You're so ratchet!
But she is a good caretaker.
Tom is looking for a bigger house to live in.
I get an error with Debug Assertion
Expression c> = -1 && c < = 255
I debugged the program and WhozCraig is right. In your input text in the line
Don’t be silly, you're going to the game!
In the word "Don’t", you do not have the normal apostrophe as you have in the word "It's" or "you're"
This special character is encoded as -110 in temp_string. In the description of std::ispunct you can read:
The behavior is undefined if the value of ch is not representable as unsigned char and is not equal to EOF.
-110 does not fit and causes a debug assertion error. If you cast it to unsigned char like WhozCraig proposed, it will work.
You can also fix your input file.
A very interesting and subtle error . . .
I have been having some problems with my code. I was asked to input elements from an .dat file into an array. For class we have to do this for various files without knowing how many elements will be in each file. The only thing we know is that here will never be more then 5000 elements per file.
One of my input file has the following elements:
5.675207 -0.571210
0.728926 0.666069
2.290909 0.751731 2.004545 0.907396
0.702893 0.646427 5.909504 -0.365045
2.082645 0.871841 5.597107 -0.633507
6.117769 -0.164663 6.091736 -0.190282
5.571074 -0.653433 4.503719 -0.978307
3.983058 -0.745620
3.670661 -0.504729
5.857438 -0.413001
When I run my code:
#define _CRT_NONSTDC_NO_DEPRECATE
#include <iostream>
#include <fstream>
#include <cstring>
using namespace std;
int main(int argc, char * argv[])
{
ifstream fin;
ofstream fout;
if (argc < 3)
{
cout << "Incorrect usage: prog.exe filenname number" << endl;
cout << "Exiting now, please try again." << endl;
return -1;
}
fin.open(argv[1]);
if (!fin)
{
cout << "Error opening file \"" << argv[1] << "\", exiting." << endl;
return -1;
}
fout.open(argv[2]);
int count = 0;
int word;
double points[5000];
while (fin >> word)
{
fin >> points[count];
++count;
}
fout << "Numer of points is: " << count/2 << endl;
for (int i = 0; i < count; i++)
{
fout << points[i] << " ";
}
fin.close();
fout.close();
return 0;
}
I outputted the elements just to make sure that they were properly inputted. I get the following and I don't know why.
0.675207 0.57121
0.728926 0.666069
0.290909 0.751731 0.004545 0.907396
0.702893 0.646427 0.909504 0.365045
0.082645 0.871841 0.597107 0.633507
0.117769 0.164663 0.091736 0.190282
0.571074 0.653433 0.503719 0.978307
0.983058 0.74562
0.670661 0.504729
0.857438 0.413001
The first digit is converted to a 0 for some reason and the negative ones become positive. Would anyone know why this is occurring?
int word;
is doing you no favours. First it's an integer so fin >> word only reads the integer portion of the inputs. 5.675207 is read as 5. the .675207 is left in the file stream for fin >> points[count]. Words isn't stored anywhere to the 5 is discarded but the .675207 lives on as 0.675207 in points[0].
Where the negative signs are going I didn't bother trying to figure out because
while (fin >> points[count])
{
++count;
}
fixes everything.
When you read in the numbers from the the file you are extracting them as "word" and then storing them as "points". "word" is an integer and "points" is a double, this will give you unexpected behavior. The compiler should give you warnings about this.
Trying to count the number of similar items in the text file after writing the text but i am getting an No operator << matches these operands operand type are std::ofstream >> std::string . Code works but when adding the while loop is where i get the error textfile >> item. Does it have anything to do with ofstream of the textfile?
#include "stdafx.h"
#include <fstream>
#include <iostream>
#include<string>
using namespace std;
int main()
{
string accord[6];
ofstream textfile;
textfile.open("C:\\temp\\1.txt");
cout << "Enter a 6 cylinder car : " << endl;
for (int x = 0; x < 6; x++) {
getline(cin, accord[x]);
}
for (int x = 0; x < 6; x++) {
textfile << accord[x] << endl;
}
int count = 0;
string item;
while (!textfile.eof()) {
textfile >> item;
if (item == "6") {
count++;
}
}
cout << count << "found!" << endl;
textfile.close();
return 0;
}
Maybe because, as the error suggests, the class std::ofstream does not have that operator.
Ofstream: Output stream class to operate on files.
As you can imagine by yourself, an output stream is an object designed to write on (output). So you're not allowed input operation.
std::fstream is a both output and input stream for file. It supports operator<< operator>>.
Variable textfile is declared as having type std::ofstream
ofstream textfile;
There is no operator >> defined for objects of this type,
You should at first close the file and use an object of type std::ifstream with this file to read data from it.
This program takes in an input, write it on a file character by character, count the amount of characters entered, then at the end copy it to an array of characters. The program works just fine until we get to the following snippet file.getline(arr, inputLength);. It changes the .txt file data and returns only the first character of the original input.
Any ideas?
#include <iostream>
#include <fstream>
using namespace std;
int getLine(char *& arr);
int main() {
char * arr = NULL;
cout << "Write something: ";
getLine(arr);
return 0;
}
int getLine(char *& arr) {
fstream file("temp.txt");
char input = '\0'; //initialize
int inputLength = 0; //initialize
if (file.is_open()) {
while (input != '\n') { //while the end of this line is not reached
input = cin.get(); //get each single character
file << input; //write it on a .txt file
inputLength++; //count the number of characters entered
}
arr = new char[inputLength]; //dynamically allocate memory for this array
file.getline(arr, inputLength); //HERE IS THE PROBLEM!!! ***
cout << "Count : " << inputLength << endl; //test counter
cout << "Array : " << arr << endl; //test line copy
file.close();
return 1;
}
return 0;
}
I see at least two problems with this code.
1) std::fstream constructor, by default, will open an existing file. It will not create a new one. If temp.txt does not exist, is_open() will fail. This code should pass the appropriate value for the second parameter to std::fstreams constructor that specifies that either a new file needs to be created, or the existing file is created.
Related to this: if the file already exists, running this code will not truncate it, so the contents of the file from this program's previous run will have obvious unexpected results.
2) The intent of this code appears to be to read back in the contents temp.txt that were previously written to it. To do that correctly, after writing and before reading it is necessary to seek back to the beginning of the file. This part appears to be missing.
There is no need in dynamic allocation because the std library functions get confused with mixed arguments such as cstring and pointer to cstring.I tested this code in Visual Studio 2015 compiler. It works good. Make sure to include all of the needed libraries:
#include <iostream>
#include <fstream>
#include<cstring>
#include<string>
using namespace std;
void getLine();
int main() {
cout << "Write something: ";
// no need to pass a pointer to a cstring
getLine();
system("pause");
return 0;
}
void getLine() {
char input[100]; // this is a cstring with
//a safe const number of elements
int inputLength; //to extract length of the actual input
//this function requires cstring as a first argument
// and constant length as a second
cin.get(input, 100, '\n'); //get each single character
//cast streamsize into int
inputLength = static_cast<int>(cin.gcount());
//testing input
cout << "Input: \n";
for (int i = 0; i < inputLength; i++)
{
cout << input[i];
}
cout << endl;
char arr[100];
strcpy_s(arr, input);
cout << "Count : " << inputLength << endl; //test counter
cout << "Array : " << endl; //test line copy
for (int i = 0; i < inputLength; i++)
{
cout << arr[i];
}
cout << endl;
// write cstring to a file
ofstream file;
file.open("temp.txt", ios::out);
if (file.is_open())
{
//write only what was entered in input
for (int i = 0; i < inputLength; i++)
file << arr[i];
file.close();
}
else cout << "Unable to open file";
}
How can I add more than one string or user input to an array? I am trying to create a contact book that requires the user to add up to 10 contacts. I am trying to store them an an array or a txt file and then later I want to be able to use this input.
Here is my code. If what I'm trying to say is not clear, running the code will help.
#include <cstdlib>
#include <iostream>
#include <fstream>
using namespace std;
int main(int argc, char *argv[])
{
// declare two variables;
char name[20];
int age;
string ans;
do {
// get user to input these;
cout << "What is your name: ";
cin >> name;
cout << "What is your age : ";
cin >> age;
cout<<"continue ";cin>>ans;
}while((ans == "y" || ans=="yes"));
// create output stream object for new file and call it fout
// use this to output data to the file "test.txt"
char filename[] = "test.txt";
ofstream fout(filename);
fout << name << "," << age << "\n"; // name, age to file
fout.close(); // close file
// output name and age : as originally entered
cout << "\n--------------------------------------------------------"
<< "\n name and age data as entered";
cout << "\n Your name is: " << name;
cout << "\n and your age is: " << age;
// output name and age : as taken from file
// first display the header
cout << "\n--------------------------------------------------------"
<< "\n name and age data from file"
<< "\n--------------------------------------------------------";
ifstream fin(filename);
char line[50];
fin.getline(line, 50);
char fname[20];
int count = 0;
do
{
fname[count] = line[count];
count++;
}
while (line[count] != ',');
fname[count] = '\0';
count++;
char fage_ch[10];
int fage_count = 0;
do
{
fage_ch[fage_count] = line[count];
fage_count++; count++;
}
while (line[count] != '\0');
fage_ch[fage_count] = '\0';
int fage_int = 0;
int total = 0;
char temp;
for (int i = 0; i < (fage_count); i++)
{
temp = fage_ch[i];
total = 10*total + atoi(&temp);
}
fage_int = total;
// display data
cout << "\n\n Your name is: " << fname;
cout << "\n and your age is: " << fage_int;
cout << "\n\n--------------------------------------------------------";
cout <<endl;
return EXIT_SUCCESS;
}
You would probably be better off using an array of structs instead of two seperate arrays to store the name & age for each entry. Then you can just loop through using strcpy to copy the input string from name into your struct's name. If you aren't comfortable with structs you could also use a couple of 2 dimensional arrays.
This looks like a homework assignment so I'm not going to post code, but for a basic algorithm to get you started (and hopefully simplify what you've got):
#define MAX_CONTACTS 10
#define MAX_NAME_LENGTH 20
// 2D array to store up to 10 names of max 20 character length
char nameVar[MAX_CONTACTS][MAX_NAME_LENGTH]
int ageVar[MAX_CONTACTS]
do until end of user input
read name into nameVar[index]
read age into ageVar[index]
index += 1
end loop
while contactCounter < index
ouput nameVar[contactCounter]
output age[contactCounter]
// you could also write to file in this loop if thats what you're trying to do
// using the fprintf function to write to an opened file
contactCounter += 1
end loop
Also, I'm not sure what you're trying to do with that atoi call, but it looks like it shouldn't be necessary. How atoi works is that it looks at the first character it is passed and it converts all of the digits until it encounters a non-digit character in the array. So if you have the char array c="123h" atoi would return 123. If you pass atoi "1h2" it will return 1.
Also you can use fprintf to print out both a char array and an int to a file.
So if you've got int i and char s[10] = "hello" and file stream you could print to stream like:
fprintf(stream, "my text to display: %s %i", s,i)
I hope that helps.