why 5/2 is not 2.5

[enqueoshy]

#include <iostream.h>
#include <math.h>

int main()
{
double resul;
resul = 5/2;
cout <<"\n resultado : " << resul;
cout <<endl;

return 0;
}

when I copile it shows
/////////////////////////
5 elevado a la 1/3 es

resultado : 2
Press any key to continue
/////////////////////////

 

[Zyrenthian]

you are dividing 2 ints and then they get promoted to a double. Make it 5.0/2 and you will get the right answer.

Matt

 

[ArkM]

Slightly detailed: in C/C++ integer (integral) division op is not the same operation as a floating point division op. It discards a fractional part of its result. Constants 5 and 2 are integers (by definition). So 5/2 == 2, that's OK.
But 5.0 is a double type constant. The 2nd operand (integer 2) promotes to 1st operand type (double), then we have float point division with result 2.5...