# How is the “exp” function used in the C language?

In the C language, the exp function is used to calculate the power of the natural logarithm base e. Its declaration is as follows:

```
double exp(double x);
```

In this case, x is the specified exponent. The exp function returns the value of e raised to the power of x.

Here is a sample code demonstrating how to use the exponential function.

```
#include <stdio.h>
#include <math.h>
int main() {
double x = 2.0;
double result = exp(x);
printf("e raised to the power of %f is %f\n", x, result);
return 0;
}
```

In the example above, we included the math.h header file, then used the exp function to calculate the power of e to the 2nd degree, and printed the result. Running the program will output:

```
e raised to the power of 2.000000 is 7.389056
```