C Data Type Range-CodePudding

I am trying to do a division of :-

#include <bits/stdc  .h>
using namespace std;

int main(){
  int A = -2147483648;
  int B = -1;
  int C = A/B;
  // this is not working
  cout<<C<<endl;
 // nor this is working
  cout<<A/B<<endl;
// But this is working
  cout<<-2147483648/-1<<endl; // printing the result 2147483648;
}

I am confused why this happening. Please explain.

CodePudding user response：

Assuming the int type is 32-bits and uses two's complement representation, the first two cases exhibit undefined behavior because both -2147483648 and -1 fit in a int but 2147483648 does not.

In the third case, the expression -2147483648/-1 contains the integer literal 2147483648 (before being negated), and has the first type in which the value can fit. In this case, that would be long int. The rest of the calculation keeps the type, so no undefined behavior occurs.

CodePudding user response：

You can change the data type to long long. long long A = -2147483648; long long B = -1; long long C = A/B; If your you need fractional result, try 'double' instead of 'long long'.