Read characters from file to end of line without using fread, fopen, fscanf, fgets

Question

This is the file contents:

Hello 
how 
are 
you

I have to read until end of line for every line because I have to work on all of these lines individually. I cannot use fread , fopen , fscanf , fgets .

Answer 1

You could reopen stdin with freopen and use getc to read bytes from the file.

If none of the stream functions from <stdio.h> are allowed, use the low level POSIX functions open and read . The manual pages are available online at man 2 open and man 2 read

#include <stdio.h>

int main() {
    if (freopen("myfile.txt", "r", stdin) != NULL) {
        char buf[1000];
        int c;
        size_t n;
        for (n = 0; n < sizeof(buf) - 1; n++) {
            c = getc(stdin);   // or c = getchar();
            if (c == EOF)
                break;
            buf[n] = c;
        }
        buf[n] = '\0';
        // the file contents are in `buf`, handle these lines as appropriate
    }
    return 0;
}