a = !5 < a; what is exactly done in this line of code?

Question

#include <iostream>
using namespace std;

int main() {
    float a =5;
    a = !5 < a;
    cout<<a;
    return 0;
}

this gives output " 1 ", help me out to understand this.

Answer 1

!something_here will evaluate to 0 except the case when something_here is 0 .

Since 0 < a , ( 0 < 5 ), a gets a value of true , which is 1 , when parsed as float.

Answer 2

!5 < a;

This is a boolean expression, resulting in true or false , when casting true to an integer or float in this case, it results in 1 , casting false gives you 0 .

To make the code a bit more understandable this is roughly equivalent:

float a =5;
bool check = !5 < a;
if(check)
  a = 1;
else
  a = 0;
cout<<a;

The expression evaluates to true because !5 == 0 and 0 < a is true .

Answer 3

Expression a = !5 < a; is equivalent to a = (a > 0) , and since a is initialized with 5 , (a > 0) gives true , which is converted to float value 1 then.

So why is a = !5 < a; equivalent to a = (a > 0) ? Expression !5 is equivalent to (5 == 0) , which is obviously false . false , when used in a comparison with a float value is converted to 0 , and 0 < a is - at least for built-in data type float - equivalent to (a > 0) .