fopen

fopen

Open a File

Portability: ISO/ANSI C conforming, UNIX compatible

SYNOPSIS
DESCRIPTION
RETURN VALUE
IMPLEMENTATION
EXAMPLE
RELATED FUNCTIONS
SEE ALSO

SYNOPSIS

#include <stdio.h>

FILE *fopen(const char *name, const char *mode);

DESCRIPTION

The fopen function opens a file and returns a pointer to the associated FILE object. The name argument is the external name (sometimes called a pathname) of the file to be opened. Its form is system dependent. The mode argument is a string defining how the file will be used. For more information about open mode values, see Open modes.

RETURN VALUE

The fopen function returns a pointer to a FILE object associated with the named file. If the file cannot be opened, a NULL value is returned.

IMPLEMENTATION

At most, 256 files can be open at one time, including the three standard files.

EXAMPLE

This example opens for a the second time to add an additional line to the file:

#include <stdio.h>

main()
{
   FILE* test;
   int c;
   float a;

   test = fopen("tso:TEST", "w");
   puts("Enter maximum speed limit in miles:");
   scanf("%d", &c);
   fprintf(test, "Maximum speed limit is %d miles/hour.\n", c);
   fclose(test);
   a = 1.619 * c;
   test = fopen("tso:TEST", "a");
   fprintf(test, "\n In km/h, the maximum speed limit is %f\n", a);
   fclose(test);
}

RELATED FUNCTIONS

afopen , freopen , open