Boolean operator

In C, both if statements and while loops rely on the idea of Boolean expressions. 

This program accepts a number from the user. It then tests the number using an if statement to see if it is less than 0. If it is, the program prints a message. Otherwise, the program is silent. The (b < 0) portion of the program is the Boolean expression. C evaluates this expression to decide whether or not to print the message. If the Boolean expression evaluates to True, then C executes the single line immediately following the if statement. If the Boolean expression is False, then C skips the line or block of lines immediately following the if statement.
 Short example:

#include <stdio.h>

#include<conio.h>

void main()
{
    int b;
    printf("Enter a value:");
    scanf("%d", &b);
    if (b < 0)
        printf("The value is negative\n");
    getch();
}

Here are all of the Boolean operators in C:

  equality          ==
  less than         <
  Greater than      >
  <=                <=
  >=                >=
  inequality        !=
  and               &&
  or                ||
  not               !