Question

void openUpNow(FILE *x, FILE *y)
{
    x = fopen("xwhatever", "r");
    y = fopen("ywhatever", "r");
}

int _tmain(int argc,  _TCHAR* argv[ ])
{   
    FILE *x, *y;

    openUpNow(x, y);
}

warning C4700: uninitialized local variable ‘x’ used

warning C4700: uninitialized local variable ‘y’ used

Remedy?

Answer 1

I don’t think that’s what you want to do anyway.

Assuming you want openUpNow() to open the files into x and y you should use:

void openUpNow(FILE **x, FILE **y)
{
    *x = fopen("xwhatever", "r");
    *y = fopen("ywhatever", "r");
}

int _tmain(int argc,  _TCHAR* argv[ ])
{   
    FILE *x, *y;

    openUpNow(&x, &y);

    //  do stuff


}

In other words, you need to pass the address of the pointers x and y into the function.

As your code is right now, the call to openUpNow() doesn’t do anything (and leaks the file-handles) since pointers are passed by value.