## Algorithm

The provided C code is a simple program that takes a user input (a double-precision floating-point number) and then checks whether the entered number is positive, negative, or zero. Here's a breakdown of the algorithm:

1. Variable Declaration:

c
```double num; ```

Declares a variable `num` of type double to store the user-entered number.

2. User Input:

c
```printf("Enter a number: "); scanf("%lf", &num); ```

Prompts the user to enter a number and reads the input into the variable `num` using `scanf`.

3. Conditional Check:

c
```if (num <= 0.0) { ```

Checks if the entered number is less than or equal to 0.

4. Nested Conditional Check:

c
```if (num == 0.0) printf("You entered 0."); else printf("You entered a negative number."); ```

If the entered number is 0, it prints "You entered 0." Otherwise, if the number is negative, it prints "You entered a negative number."

5. Else Block:

c
```else printf("You entered a positive number."); ```

If the entered number is greater than 0, it prints "You entered a positive number."

6. Program End:

c
```return 0; ```

Indicates the successful execution of the program.

## Code Examples

### #1 Code Example- Check Positive or Negative Using Nested if...else

```Code - C Programming```

``````#include <stdio.h>

int main() {

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

if (num < 0.0)
printf("You entered a negative number.");
else if (num > 0.0)
printf("You entered a positive number.");
else
printf("You entered 0.");

return 0;
}
``````
Copy The Code &

Output

cmd
Enter a number: 12.3
You entered a positive number.

### #2 CodeExample-Check Positive or Negative Using if...else Ladder

```Code - C Programming```

``````#include <stdio.h>

int main() {

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

if (num < 0.0)
printf("You entered a negative number.");
else if (num > 0.0)
printf("You entered a positive number.");
else
printf("You entered 0.");

return 0;
}
``````
Copy The Code &

Output

cmd
Enter a number: 0
You entered 0.