C Programming: Drag&Drop a file over a program's icon

i just made a little program that reads the name of a file dragged over it's icon and writes it into an output text file

but if i compile this 开发者_开发知识库program, it crashes when i try to drag a file over it. if i open it with a doble click it's ok; if i open it with command line and parameters it's ok; but if i just drop a file over the program i have compiled, it always crashes and i don't know why

just try to compile like this:

#include <stdio.h>

int main(int argc, char * argv[])
{
    FILE * File=fopen("file.txt", "w");
    fclose(File);
    return 0;
}

if you drag&drop a simple file over that program icon, the program crashes

does anyone knows why?

---

You are probably making assumptions about the current working directory and its permissions when your executable runs. Calling fclose on an invalid FILE * (e.g. NULL) will most likely result in a crash. You need to verify that fopen succeeds, e.g.

#include <stdio.h>

int main(int argc, char * argv[])
{
    FILE * f = fopen("file.txt", "w");
    if (f != NULL)
    {
        //
        // write stuff to file here if you want...
        //
        fclose(f);
    }
    return 0;
}