The return statement is used to immediately return from the current function. It is illegal outside of the body of a function definition. If the function returns a value then the return statement must be accompanied by a return value of the correct type.

int difference(int a, int b)
{
    // Must return a value regardless of the control path taken
    if(a < b)
        return b - a;
    else
        return a - b;
}