Question

Possible Duplicate:
Why can you return from a non-void function without returning a value without producing a compiler error?

void main()
{
    int y=0;
    clrscr();
    printf("%d\n",Testing());
    y=Testing();
    printf("%d",y);
    getch();
}
int  Testing()
{
    int x=100;
    //return x;
}

Result 
512
4

i am not returning any thing from the testing function still value is coming?

Another Question also

void main()
{
    char Testing();
    int y=0;
    clrscr();
    printf("%d\n",Testing());
    if(Testing())
        printf("if--exi");
    else
        printf("else--exi");
    getch();
}
char Testing()
{
    char y;
    //return y;
}

Result

0
if--exi

if printf is commented then result is

else--exi

why is it happening like that

Answer 1

A function declared to return a value that reaches a path without a return has undefined behavior. You just got unlucky that it appeared to still be returning a semi-plausible value. The compiler assumes that a return is called in all exits from the function and that a return value will be available at a particular location.

In your second example effectively anything can happen, including returning different values each call.

g++ has a warning to detect this problem, and it’s highly worth enabling.