14. Write a program in C to check if a number is negative without using the 'if' statement.

In this tutorial post, we will learn how to write a C program to test whether a value is positive or negative without using conditional statements. We will write a C program to test whether a value is positive or negative without using conditional statements. It's hard to test positive and negative numbers without if-else statements, we only use bitwise operators.
Input: 25
Output: 25 is positive
Input: -100
Output: -100 is negative
Input: 0
Output: 0 is zero
Signed Shift Data >>(BITS-1) Converts every negative number to -1 and all others to 0, where bits is the number of bits in the whole number. As we do - data>>(BITS-1), if the data is a positive number it will return -1, as we do - data>>(BITS-1).
But both will return 0 for zero value (0), so we can build a formula here: (1 + (data>>(BITS-1)) -(-data>>(BITS-1)));
BITS=> Number of bits in a whole integer number.

a program in C language to to find the negative number without using the if statement

Let us study and check the result of the above formula for positive, negative, and zero,
1. When data is negative integer number:
1 + (-1) - 0 => 0

2. When data is a positive integer number:
1 + 0 - (-1) => 2
3. When data is zero 0:
1 + 0 - 0 => 1
So we know that the above formula returns 2 for a positive number, 0 for a negative number, 1 for zero.
If you don't want to use conditional if-else statement or ternary operator ? to find positive and negative numbers in C programming. So, you need to create an array of strings with "negative" at the 0th index, "zero" at the first index and "positive " in the second index.
You want to calculate the index using the above formula and print the row as per the index.
Let's look at a C program that checks positive, negative and zero without if else branch statement.

#include <stdio.h>
// Total numbers of bits required to represent integer
#define BITS sizeof(int) * 8
// 0 if it is negative
// 1 if it is zero
// returns 2 if it is positive
int main()
{
int n,numType;
// str array is string array that stores all kinds of number
const char* str[] = { "Negative", "Zero", "Positive" };
printf("Enter any number: ");
scanf("%d", &n);
//Calling function to get index
numType = (1 + (n>>(BITS -1)) -(-n>>(BITS -1)));
printf("%d is %s",n,str[numType]);
return 0;
}
Output:
Enter any number: -10
Negative number
Enter any number: 10
Positive number
Enter any number: 0
Zero

Other Topic:-->>Nested While Loop. || conditional statements Assignments in C.