ftell.gml

开放源码的编译器open watcom 1.6.0版的源代码

.func ftell
#include <stdio.h>
long int ftell( FILE *fp );
.ixfunc2 '&StrIo' &func
.funcend
.desc begin
The &func function returns the current read/write position
of the file specified by
.arg fp.
This position defines the character that will be read or written by the
next I/O operation on the file.
The value returned by &func can be used in a subsequent call to
.kw fseek
to set the file to the same position.
.desc end
.return begin
The &func function returns the current read/write position
of the file specified by
.arg fp.
When an error is detected,
.mono -1L
is returned.
.im errnoref
.return end
.see begin
.seelist ftell fgetpos fopen fsetpos fseek
.see end
.exmp begin
#include <stdio.h>
.exmp break
long int filesize( FILE *fp )
  {
    long int save_pos, size_of_file;
.exmp break
    save_pos = ftell( fp );
    fseek( fp, 0L, SEEK_END );
    size_of_file = ftell( fp );
    fseek( fp, save_pos, SEEK_SET );
    return( size_of_file );
  }
.exmp break
void main()
  {
    FILE *fp;

    fp = fopen( "file", "r" );
    if( fp != NULL ) {
      printf( "File size=%ld\n", filesize( fp ) );
      fclose( fp );
    }
  }
.exmp end
.class ANSI
.system