Conditionals


C# uses Boolean variables to evaluate conditions. The Boolean values true and false are returned when an expression is compared or evaluated. For example:

int a = 4;
bool b = a == 4;

if (b) {
    Console.WriteLine("It's true!");
}

Of course we don't normally assign a conditional expression to a bool, we just use the short version:

int a = 4;

if (a == 4) {
    Console.WriteLine("Ohhh! So a is 4!");
}

Boolean operators

There aren't that many operators to use in conditional statements and most of them are pretty straight forward:

int a = 4;
int b = 5;
bool result;
result = a < b; // true
result = a > b; // false
result = a <= 4; // a smaller or equal to 4 - true
result = b >= 6; // b bigger or equal to 6 - false
result = a == b; // a equal to b - false
result = a != b; // a is not equal to b - true
result = a > b || a < b; // Logical or - true
result = 3 < a && a < 6; // Logical and - true
result = !result; // Logical not - false

if - else and between

The if, else statement in C# is pretty simple.

if (a == b) {
    // a and b are equal, let's do something cool
}

And we can also add an else statement after an if, to do something if the condition is not true

if (a == b) {
    // We already know this part
} else {
    // a and b are not equal... :/
}

The if - else statements doesn't have to be in several lines with {}, if can be used in one line, or without the {}, for a single line statment.

if (a == b)
    Console.WriteLine("Another line Wow!");
else
    Console.WriteLine("Double rainbow!");

Although this method might be useful for making your code shorter by using fewer lines, we strongly recommend for beginners not to use this short version of statements and always use the full version with {}. This goes to every statement that can be shorted to a single line (for, while, etc).

Exercise

In this exercise, you must construct an if statement that checks if the number guess is equal to 500. If that is the case, use Console.WriteLine to display "Success!".