osource's blog

C++ how to check for overflow in long long
By osource, history, 3 years ago, In English

let's say I have 2 numbers x and y. How do I check if x*y results in an overflow in C++?. Both x and y are long long int.

  • Vote: I like it
  • +1
  • Vote: I do not like it

Comments Comments (2)
| Write comment?
»
3 years ago, # |
← Rev. 2   Vote: I like it 0 Vote: I do not like it

if x>LLONG_MAX/y(or y>LLONG_MAX/x), then overflow

→ Reply
»
3 years ago, # |
  Vote: I like it 0 Vote: I do not like it 
long long mul = a * b;
if (mul / a != b) {
  //overflowed
}
→ Reply