Big number A+B

The problem A+B is probably the easiest problem, however, the maxim number C/C++ can calculate is between -9223372036854775808~9223372036854775807. The bigger number can’t be calculate unless you use Python or Java. So I’m going to introduce a way to calculate the big number of A+B.

Check for alphabet characters

A quick way to check whether the character a is a function is to use the function isalpha(a). If is lower case, return 1; If is upper case, return 2; If is not an alphabet, return 0;

The header file of it is < iostream > or < cctype >.