In this C++ tutorial, you will learn how to find the largest of the two given values using fmax() function of cmath, with syntax and examples.

## C++ fmax()

C++ fmax() returns largest of the two values given as arguments.

## Syntax

The syntax of C++ fmax() is

`fmax(x, y)`

where

Returns

The return value depends on the type of value passed for parameter x.

The return value of fmax(x) is

• double if x is double.
• float if x is float.
• long double if x is long double.
• Promoted if x and y are of different types. Promoted is long double if any of the argument is long double, else the Promoted is double.

The synopsis of fmax() function is

```double fmax(double x, double y);
float fmax(float x, float y);
long double fmax(long double x, long double y);
Promoted fmax(Type1 x, Type2 y); // for combinations of integral types```

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

## Example

In this example, we read two values from user into variables x and y, and compute the largest of these two values using fmax() function.

C++ Program

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

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

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

Output

```Enter a value (x) : 14.2
Enter a value (y) : 2.6
fmax(14.2, 2.6) : 14.2
Program ended with exit code: 0```
```Enter a value (x) : -5
Enter a value (y) : -99
fmax(-5, -99) : -5
Program ended with exit code: 0```

If one of the values: x or y; is nan, then the other value is returned.

```Enter a value (x) : nan
Enter a value (y) : 5
fmax(nan, 5) : 5
Program ended with exit code: 0```

## Conclusion

In this C++ Tutorial, we learned the syntax of C++ fmax(), and how to use this function to find the largest of two values, with the help of examples.