Tag Archives: comparisons

Making comparisons in C# (if, else if, and else statements)

In this tutorial you will learn how to make comparisons in C# using the following conditional statements:

  • if
  • else if
  • else

We can check, for example, if a number is less than, greater than, less than or equal to, greater than or equal to, equal to, or not equal to another number. We can also check if a string variable is equal to another string value (for example, checking if a password is correct). To make comparisons, we will need to be familiar with comparison operators.

Comparison operators

Comparison (or equality) operators are used to compare two values. The result of using an equality operator can either be true or false. The only type of variable that can store the result of an equality operator is a Boolean. The table below describes the comparison operators used in C#.

Operator Description
== This operator is used to check if two values are equal eg. x == 5 would return true if x had a value of 5.
> and < The ‘greater than’ and ‘less than’ operators are used to check if values are greater than or less than another value. For example, x > 5 (if the value of x was 3 than it would return false).
>= and <= The ‘greater than or equal to’ and ‘less than or equal to’ operators are similar to the ‘greater than’ and ‘less than’ operators. For examples, 5>=5 would return true because 5 is equal to 5, and 6<=10 would return true because 6 is less than 10.
!= The ‘not equal’ operator is used to check if two values are not the same as each other. For example, x != 10 would return true if the value of x was 9 because 9 is not equal to 10. However, y != 5 would return false if the value of y was 5.

Watch the video below which shows how to make comparisons using if, else if, and else statements (scroll down for the sample code).

Sample code

using System;

namespace MyCSharpProject
{
  class MainClass
  {
    public static void Main(string[] args)
    {
      int x = 11;

      if (x > 10)
      {
        Console.WriteLine("x is greater than 10");
      }
      else if (x < 10)
      {
        Console.WriteLine("x is less than 10");
      }
      else{
        Console.WriteLine("x is equal to 10");
      }
    }
  }
}

Logical operators

We can also check if multiple conditions evaluate to true or if at least one of multiple conditions evaluate to true in a single if statement using logical operators. Logical operators are used for complex conditions. The table below describes each logical operator.

Operator Description
&& This is known as the AND operator and is used to check if both values are true in a complex condition.
|| The is known as the OR operator and is used to check if at least one of the values is true when two values are compared. It will return true if either one or both values are true.
! This is known as the NOT operator and will return the opposite of a Boolean value. For example !true; would return false and !false; would return true.

Here is an example of using the && logical operator to display a message only if a user’s first name is “Joe” AND their last name is also “Bloggs”.

if (firstName == "Joe" && lastName == "Bloggs")
{
   Console.WriteLine("Hello Joe Bloggs.");
}
else
{
   Console.WriteLine("I don't know you.");
}

Watch the video below to see how you can use logical operators in conditional statements and then scroll down for the sample code.

Sample code using logical OR operator

using System;

namespace MyCSharpProject
{
  class MainClass
  {
    public static void Main(string[] args)
    {
      string firstName = "Joe";
      string lastName = "Smith";

      if (firstName == "Joe" || lastName == "Bloggs")
      {
        Console.WriteLine("Hi Joe.");
      }
      else{
        Console.WriteLine("I don't know you.");
      }
    }
  }
}

Sample code using logical AND operator

using System;

namespace MyCSharpProject
{
  class MainClass
  {
    public static void Main(string[] args)
    {
      string firstName = "Joe";
      string lastName = "Bloggs";

      if (firstName == "Joe" && lastName == "Bloggs")
      {
        Console.WriteLine("Hi Joe.");
      }
      else{
        Console.WriteLine("I don't know you.");
      }
    }
  }
}

Next tutorial: Switch statements in C#