file_exists
This function checks whether a given file exists.
bool file_exists(string filename)
Parameters:
filename
The name of the file to search for.
Return value:
true if the file exists, false otherwise.
Remarks:
This function works with both absolute and relative paths.
Example:

    // Check if notepad.exe exists in the Windows directory.

    void main()
    {
    if(file_exists("C:\\windows\\notepad.exe"))
    {
    alert("Information", "Notepad exists.");
    }
    else
    {
    alert("Oops", "You broke notepad! It's sort of a nice program...");
    }
    }