need some help please

[nurulhuda]

Hello,
QUESTION: why price input as 10000 then the value of payment is 0?

#include <iostream>
using namespace std;

int main()
{
float price, payment;

cout << "\n PAYMENT OF A CAR AFTER 5% DISCOUNT:";
cout << "\n -----------------------------------";

cout << "\n Enter the car price: ";
cin >> price;
payment = 95/100*price;

cout << "\n OUTPUT: "<< payment;
return 0;
}

[Ganado]

95/100 (left-to-right associativity) does integer division. The result is 0, because it rounds down to the nearest integer. And then 0 times anything is 0.

To prevent this, make at least one of the operands a floating-point type.

ex: payment = 95.0/100*price;

Here is an SO link that explains it in more detail: https://stackoverflow.com/questions/3602827/what-is-the-behavior-of-integer-division

[kbw]

It's what we call the order of precedence of operators.
https://msdn.microsoft.com/en-us/library/2bxt6kc4.aspx

Consider payment = 95/100*payment;

95/100 is executed first. As they are integers, the value is zero. Then that zero is used to multiply payment.

You can force the correct behaviour by using double constants.
payment = 95.0/100.0*payment;

[nurulhuda]

i thought if we already declared price and payment as float the output will be in float (correct)? what is the explanation for this? tqvm.

[JLBorges]

95/100*price is parsed as (95/100) * price
(multiplication and division have equal precedence, they associate from left-to-right.)

Evaluated "as if":

const int a = (95/100) ; // both operands are of type int, integer division, result is 0

const float b = float(a) ; // convert the result of the integer division to float, result is 0.0f
// see: usual arithmetic conversions http://en.cppreference.com/w/c/language/conversion

const float c = b * price ; // this is the result of the value computation of 95/100*price

payment = c ; // assign the result to payment 

Note: strongly favour using double as the default floating point type.