How to avoid integer overflow?

Question

In the following C ++ code, 32767 + 1 = -32768.

#include <iostream>
int main(){
short var = 32767;
var++;
std::cout << var;
std::cin.get();
}

Is there a way to just leave "var" as 32767, with no errors?

Answer 1

Yes there is:

if (var < 32767) var++;

By the way, you shouldn't hard code the constant, use the ones numeric_limits<short>::max()defined in the header instead <limits>.

You can encapsulate this functionality in a function template:

template <class T>
void increment_without_wraparound(T& value) {
   if (value < numeric_limits<T>::max())
     value++;
}

and use it like:

short var = 32767;
increment_without_wraparound(var); // pick a shorter name!

Answer 2

#include <iostream> 
int main(){ 
unsigned short var = 32767; 
var++; 
std::cout << var; 
std::cin.get(); 
} 

Answer 3

'unsigned short int' 'long int'

#include <iostream>
int main(){
long int var = 32767;
var++;
std::cout << var;
std::cin.get();
}