Question

char input1;
std::cout << "input1 : ";
std::cin >> input1;

int input2;
std::cout << "input2 : ";
std::cin >> input2;

std::cout << input1 << std::endl;
std::cout << input2 << std::endl;

return 0;

I wrote ‘a’ at input1 and ‘a’ at input2.

Ouput is like this.
input1 : a
input2 : a
a
-858993460

I’m curious…’a’ charter is 97 in dec. why does it print -858993460?
‘a’ is not converted to 97 automatically? why?

Answer 1

a, as a string, is not convertible to an int by the rules std::cin follows. Consider this: a is not a valid integer in base 10. std::cin will fail to convert the string "a" to an int.

The reason it prints -858993460 is because the int is not initialized, so it could print anything, or nothing, or do whatever it desires (look up undefined behaviour).

Try something like this instead:

char input2_chr;
std::cin >> input2_chr;
int input2 = input2_chr;