Integer division in c++ as opposed to real division

[theengineer]

I have the following details
double x= 1.5
double y= -1.5
int m= 20
int n= 4

my question is 5 * x – n / 5 at which what would n / 5 equal to, I think its zero since its integer division? or would the 5 be considered a real number?

[stdq]

If n is an integer, and 5 is an integer literal, the result is 5 / 4 without the floating-point part, that is, the result is 1.20 with the 0.20 part discarded - in other words, the result is 1. If you want the result to be 1.20, you can do this (note the use of 5.0 instead of 5):

n / 5.0

or this:

( ( double ) n ) / 5

or even this:

n / ( ( double ) 5 )

( double ) is a cast operator. It is being used to create a floating-point temporary copy of its operand, which is n or 5, depending on your choice.

Remember: in C, a division with both operands being integers results in an integer (this is called integer division, I think). You can follow one of the approaches I mentioned above so that when of the operands of / is a floating-point value, resulting in floating-point division.

Best,
stdq

[weaknessforcats]

Firstly, the posted code won't compile.

After it compiles, you process 5 * x where x is a double. So 5 is promoted to double and the result is double. That would be 7.5.

Next you do n/5. Multiplication and division are done before addition and subtraction. n/5 is really 4/5, which is 0 because 5 goes into 4 zero times. (integer division).

Next you do 7.5 - 0. In this case 0 is promoted to double. And there is the final answer: 7.5.