Thread: Writing Output to a File

I am new to C programming. I just started reading through the K&R section on character input and output, but I am left wondering how a person would go about writing text to a file.

I'm not looking to do anything elaborate with it just yet ... I would like to write output from the code from the exercises that I do to a file so that I can better view the results (the Windows display disappears almost instantly).

Any suggestions?

So if I wanted to print "Hello World" to a file called test.txt, I would use those functions to do so?

If so, how would the "Hello World" know where the file it's being written to is? Would I have to add test.txt as a parameter to the functions you mentioned?

You use something called a file pointer (type FILE*) like this:

Code:

#include <stdio.h>

#define MAXSTR 1000

int main() {
    char str[ MAXSTR ];
    FILE* fp = fopen( "test.txt", "w" );  /* w = write */
    fprintf( fp, "Hello, world!\n" );
    fclose( fp );

    fp = fopen( "test.txt", "r" );  /* r = read */
    fgets( str, MAXSTR, fp );
    puts( str );
    fclose( fp );
}

Originally Posted by portable

(the Windows display disappears almost instantly).

Any suggestions?

you can add system ("PAUSE") (if I remember well) to see what it is displaying

Code:

#include <stdlib.h>
int main()
{
    //code

    system("PAUSE"); 
    return 0;
}

I am able to follow the code for the file pointer, which was a big help. Thanks to both ooga and alreadyinuse

Thanks laser

Is there a way to see a list of all of the commonly used functions, such as the ones mentioned in this thread, and what they do? I know a lot of the names are self explanatory, but it would be nice to see them laid out in a study-able format.

Like I said in the original post, I'm new, and I want to learn as much as possible

http://www.cplusplus.com/
http://www.cppreference.com/

look at your PM