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c++pointersoperator-precedencepostfix-operator

dereference and suffix ++ precedence

int a[3]={10,20,30};
int* p = a;
cout << *p++ << endl;

According to wikipedia, suffix ++ has higher precedence than dereference, *p++ should run p++ first and then dereference and the result should be 20, but why the actual result is 10?

Solution

  • p++ uses the postfix increment operator. I.e., it increments p, but returns the value that was present before incrementing. In other words, this is equivalent of doing something like this:

    int a[3]={10,20,30};
int* p = a;
int* q = p;
++p;
cout << *q << endl;

    When styled like that, it's obvious why 10 is printed. If you want to increment p and print its dereference, you could use the prefix increment operator:

    int a[3]={10,20,30};
int* p = a;
cout << *(++p) << endl;