## Quick links

Write a C program to input a number and check positive negative or zero using switch case. Checking negative, positive or zero using switch case is little tricky. In this example, I will explain how to check positive negative or zero using switch case. However, it is not recommended way, it’s just for learning.

**Example**

**Input**

Input number: 23

**Output**

23 is positive

## Required knowledge

Basic Input Output, Switch case

## How to check positive negative or zero using switch case

We already know how to check whether a number is positive, negative or zero using if else if. However, checking using switch case if little tricky since, `switch`

works with constants.

Switch case expects an expression that must return a list of known constant. So first let us define expressions to check positive, negative or zero.

`(num > 0)`

return 1 (`true`

) for positive number, otherwise 0 (`false`

).

`(num < 0)`

check negative and return 1 for negative number, otherwise 0.

`(num == 0)`

return 1 for zero, otherwise 0.

Next, to code this we will require nested `switch`

. Step by step descriptive logic to check positive negative or zero using switch case.

- Input number from user, store it in some variable say
`num`. - First we will check for positive. Use expression to check positive in outer switch. Use
`switch(num > 0)`

. - The above switch expression with either return 1 or 0. Hence for
`case 1:`

print positive number. - For
`case 0:`

write one more nested switch statement with expression to check negative number. Say`switch (num < 0)`

. - For above switch expression the number can either be negative or zero. Since outer switch already says its not positive.
- Hence for
`case 1:`

print negative and for`case 0:`

print zero.

## Program to check positive negative or zero using switch case

```
/**
* C program to check positive negative or zero using switch case
*/
#include <stdio.h>
int main()
{
int num;
printf("Enter any number: ");
scanf("%d", &num);
switch (num > 0)
{
// Num is positive
case 1:
printf("%d is positive.", num);
break;
// Num is either negative or zero
case 0:
switch (num < 0)
{
case 1:
printf("%d is negative.", num);
break;
case 0:
printf("%d is zero.", num);
break;
}
break;
}
return 0;
}
```

Output

Enter any number: 23 23 is positive. Enter any number: -22 -22 is negative. Enter any number: 0 0 is zero.

Happy coding ðŸ˜‰

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