Combine sizeof string and chararcter

Question

The last 2 cout statements have the same size. why?

int main() 
{
char ch=127;
cout<<sizeof(ch)<<endl;    //Size=1
cout<<sizeof("Hello")<<endl;    //Size=6
cout<<sizeof("Hello"+ch)<<endl;    //Size=8
cout<<sizeof("HelloWorld"+ch)<<endl;    //Size=8
return 0;
}

Please explain. Thanks

Answer 1

When you do "Hello"+ch the array containing the string "Hello" decays to a pointer to its first element, and you add ch to this pointer.

The result of pointer arithmetic is a pointer, which is what you get the size of.

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Equivalent code would be something like

char const hello[] = "Hello";
char const* phello = hello;  // equivalent to &hello[0]
char const* result = phello + ch;
cout << sizeof(result) << endl;