# C program to Check Whether a Number is Positive or Negative

In programming, it is often necessary to check whether a number is positive or negative. In this program, we will write a C program that prompts the user to enter a number, checks whether the number is positive or negative, and prints the result.

Problem Statement

The problem statement is to write a C program that prompts the user to enter a number, checks whether the number is positive or negative, and prints the result.

Solution

Here is the C program to check whether a number is positive or negative:

```#include <stdio.h>

int main() {
int num;

printf("Enter a number: ");
scanf("%d", &num);

if (num > 0) {
printf("%d is positive\n", num);
} else if (num < 0) {
printf("%d is negative\n", num);
} else {
printf("Number is zero\n");
}

return 0;
}
```

Output

Explanation

First, we include the `stdio.h` header file which is used for input/output functions. Then, we define the `main()` function as the starting point of our program.

We declare an integer variable `num` which will be used to store the number entered by the user.

Next, we prompt the user to enter a number using the `printf()` function. The `scanf()` function is used to read in the number entered by the user. The first parameter to `scanf()` is the format string “%d” which specifies that the input should be read in as an integer. The second parameter is the address of the `num` variable where the input should be stored.

We then use an if-else statement to determine whether the number is positive, negative, or zero. If the number is greater than 0, we print that the number is positive using the `printf()` function. If the number is less than 0, we print that the number is negative. If the number is 0, we print that the number is zero.

Finally, we return 0 to indicate that the program executed successfully.

Conclusion

In this tutorial, we learned how to write a C program to check whether a number is positive or negative. We used the `scanf()` function to read in the number entered by the user, and we used an if-else statement to determine whether the number is positive, negative, or zero. We then printed the appropriate message using the `printf()` function.