SAS/C Library Reference, Vol. 1

fopen -- Open a File

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 %fn", a);
     fclose(test);
  }

RELATED FUNCTIONS

afopen, freopen, open