C Programming — The if Statement

#include <stdio.h>

#include <conio.h>

int main()

{

int number1, number2;

printf("Enter two numbers:\n");

scanf("%d %d", &number1, &number2);

if ( number1 == number2 )

printf("%d is equal to %d\n", number1, number2);

if ( number1 != number2 )

printf("%d is not equal to %d\n", number1, number2);

if ( number1 < number2 )

printf("%d is less than %d\n", number1, number2);

if ( number1 > number2 )

printf("%d is greater than %d\n", number1, number2)

if ( number1 <= number2 )

printf("%d is less than or equal to %d\n", number1, number2);

if ( number1 >= number2 )

printf("%d is greater than or equal to %d\n", number1, number2);

if ( number1 % 2 == 0)

printf("number1 is even");

else

printf("number1 is odd");

getch();

return 0;

}

The conditions use parentheses and compare two variables with the comparison operators `==`, `!=`, `<`, `>`, `<=` and `>=`.

There are two possible outcomes. When the condition is true, the statement after `if` is executed; otherwise it is skipped. For a single statement this continues up to the terminating semicolon. Multiple statements must be placed between braces `{` and `}`.

Notice that comparison uses two equals signs (`==`). A single equals sign (`=`) is the assignment operator and is not used for equality comparison.

The percent sign (`%`) performs the modulo operation. If the result is zero, the number is evenly divisible. In this example, a true condition prints that `number1` is even.

When the condition is false, the statement after `else` is executed, so the program prints that `number1` is odd.

Also notice that no semicolon is placed immediately after the `if` or `else` keywords.