In this C++ tutorial, you will learn how to find the positive different between two given numbers using fdim() function of cmath, with syntax and examples.

## C++ fdim()

C++ fdim(x, y) returns positive different between x and y.

fdim() returns x-y if x>=0, else it returns 0.

## Syntax

The syntax of C++ fdim() is

`fdim(x, y)`

where

Returns

The return value depends on the type of value passed for parameters x and y. The return value of fdim() is

• double if x and y are double.
• float if x and y are float.
• long double if x and y are long double.
• Promoted to the higher of the given arguments for integral type arguments.

The synopsis of fdim() function is

```double fdim(double x, double y);
float fdim(float x, float y);
long double fdim(long double x, long double y);
Promoted fdim(Type1 x, Type2 y); // for integral type argument values```

fdim() is a function of cmath library. Include cmath library at the start of program, if using fdim() function.

## Example

In this example, we read two values from user into x and y, and find the positive difference of x and y using fdim(x, y) function.

C++ Program

```#include <iostream>
#include<cmath>
using namespace std;

int main() {
double x, y;
cout << "Enter x : ";
cin >> x;
cout << "Enter y : ";
cin >> y;

double result = fdim(x, y);
cout << "fdim(x, y) : " << result << endl;
}```

Output

```Enter x : 24
Enter y : 15
fdim(x, y) : 9
Program ended with exit code: 0```

Since x-y is greater than 0, fdim(x, y) returns the difference of x and y.

Run#2

```Enter x : 23
Enter y : 68
fdim(x, y) : 0
Program ended with exit code: 0```

Since x-y is greater than 0, fdim(x, y) returns 0.

## Conclusion

In this C++ Tutorial, we learned the syntax of C++ fdim(), and how to use this function to find the positive difference, with the help of examples.