standard.C.io.fsize

fsize is available since version 1.0.

Prototype:

number fsize(number fd)

Parameters

fd
[in] A valid file descriptor

Description:

Gets the file length, in bytes, of the target file.

Return value:

Returns the file length, in bytes, of the target file

Example
import standard.C.io

define FILENAME          "test.txt"

class Main {
     function Main() {
          if(!(var fd = fopen( FILENAME, "r" )))
               echo "The file " + FILENAME + " was not opened\n";
          else {               
               var buffer = "";
               fread(buffer, 1, fsize(fd), fd);
               echo buffer;
               fclose(fd);
          }
     }
}  

Results 
Content of the file