# What is the usage of the sign function in the C language?

In the C language, the sign function is typically used to return the sign of a number, determining if it is positive, negative, or zero. Its prototype is defined as:

```
int sign(int x);
```

The parameter x is the number for which the sign needs to be determined, and the function returns:

- Return 1 if x is greater than 0.
- If x is equal to 0, return 0.
- If x is less than 0, return -1.

The sample code is shown below:

```
#include <stdio.h>
int sign(int x){
if(x > 0){
return 1;
}else if(x == 0){
return 0;
}else{
return -1;
}
}
int main(){
int num = 10;
printf("The sign of %d is: %d\n", num, sign(num));
num = -5;
printf("The sign of %d is: %d\n", num, sign(num));
num = 0;
printf("The sign of %d is: %d\n", num, sign(num));
return 0;
}
```

The output result is:

```
The sign of 10 is: 1
The sign of -5 is: -1
The sign of 0 is: 0
```