pointer question

Question

void foo(int*);
int main()
{
 int i = 10;
 foo((&i)++);
}
void foo(int *p)
{
printf("%d\n", *p);
}

It gives compile time error but how? which particular statement is cause of this error in program?

Answer 1

The Increment operator requires lvalue is an expression referring to an object. 

We know that,

int a = 10; // a is lvalue expression and 10 is rvalue which is usually a constant.

 int *p = &a; // Note that  An lvalue can also be an rvalue or can be used in rvalue, but an rvalue can never be an lvalue.

From the above statement &lvalue is a rvalue.

&i ++ = (rvalue)++, but increment operator requires lvalue as its operand. Hence compiler error.

Error can be resolved as ,

    int i = 10;
    int *p = &i;
    foo(p++); 

Comments

thank you :)