how to stop reading when i find end of line

Question

i m trying to read from a file and stop when i hit end of line. the thing is, it doesnt seem to work.¯_(ツ)_/¯ any ideas why?

#include <iostream>
#include <fstream>
using namespace std;

int main(){
    char a;
    ifstream myfile;
    myfile.open("text.txt");
    while (!myfile.eof())
    {
    myfile>> a;
    if (a=='\n')
    cout << "end of line";

    }
myfile.close();
}

text file i read:

`while (!myfile.eof())` [is always wrong](http://stackoverflow.com/questions/5605125/why-is-iostreameof-inside-a-loop-condition-considered-wrong). — melpomene, Apr 30 '17 at 12:21
"doesn't seem to work" is not a problem description. What is it actually doing? — melpomene, Apr 30 '17 at 12:22
it does not locate the change of line. never types "end of line" — Βασιλική Νικολάου, Apr 30 '17 at 12:27
1) why is while (!myfile.eof()) always wrong? i want to check if i have finished reading my file — Βασιλική Νικολάου, Apr 30 '17 at 12:32
2) i am running it in code blocks, it returns 0 but it never shows "end of line" as it is supposed to — Βασιλική Νικολάου, Apr 30 '17 at 12:33

score 1 · Answer 1 · answered Apr 30 '17 at 12:27

1

Try while (myfile.get(a)) instead?

while (myfile.get(a))
{
    if (a=='\n')
        cout << "end of line";

}

answered Apr 30 '17 at 12:27

siamezzze

81
3
5

@deW1 the example from the question was about character-by-character read, I assumed there is a reason for it. Sure, there is more than one way to do it, as shown in other answers. – siamezzze Apr 30 '17 at 12:49

score 1 · Answer 2 · answered Apr 30 '17 at 12:49

Why make things harder than needed. If you want to parse lines, then use std::getline().

#include <iostream>
#include <fstream>

int main(int argc, char *argv[]) {
    std::ifstream myfile("text.txt");

    std::string line;
    while (std::getline(myfile, line)) {
        std::cout << "end of line" << std::endl;
    }
}

score 0 · Answer 3 · answered Apr 30 '17 at 12:44

0

using a for loop

std::ifstream ifs( "file" );
for( char chr = 0; ifs.peek() != '\n'; ifs.get( chr ) ){
    std::cout << chr;
}
ifs.close();

answered Apr 30 '17 at 12:44

Shakiba Moshiri

13,741
2
20
35

score 0 · Answer 4 · answered Apr 30 '17 at 12:48

I just rewrite your code:

#include <iostream>
#include <fstream>
using namespace std;

int main(){
    char a;
    ifstream myfile;
    myfile.open("/Users/sijan/CLionProjects/test2/text.txt",ifstream::in);
    while (myfile.get(a))
    {
        cout<< a;

        if (a=='\n')
            cout << "end of line\n";
    }

    if (myfile.eof())
        cout << "end of file";
    myfile.close();
}

how to stop reading when i find end of line

4 Answers4