C# Ternary operator

C# uses something called a ternary operator to provide a shortcut way of making decisions. 

The syntax of the ternary operator is as follows:

[condition] ? [true expression] : [false expression]

The way this works is that [condition] is replaced with an expression that will return either true or false.

If the result is true then the expression that replaces the [true expression] is evaluated. Conversely, if the result was false then the [false expression] is evaluated. 

Let's see this in action:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace HelloWorld
{
    class Program
    {
        static void Main(string[] args)
        {
            int x = 10;
            int y = 20;

            Console.WriteLine(x > y ? x : y);
// output = 20
            Console.ReadLine();
        }
    }
}

The above code example will evaluate whether x is greater than y. Clearly this will evaluate to false resulting in y being returned to the WriteLine method for display to the user.

C# Ternary operator has the form: q ? a : b => if condition q is true, a is evaluated, else b is evaluated.

For example the following code use ternary to get the bigger value of two.

int Max (int a, int b)
{
       return (a > b) ? a : b;
}

We can use the if statement to code the same logic:

if(a > b){
  return a;
}else{
  return b;
}

1 - Comparison of Two Values Using If Else

Consider the below C# program for comparison of two values using the if-else statement:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace HelloWorld
{
    class Program
    {
        static void Main(string[] args)
        {
            int a = 40;
            int b = 50;
            if (a < b)
            {
                Console.WriteLine("a's value is less than b");
            }
            else
            {
                Console.WriteLine("b's value is less than a");
            }
            Console.ReadLine();
        }
    }
}

Output:

In the above program, two variables, a and b, are defined and assigned some values. Their values are compared against each other to find out which is greater using if-else conditional statements.

2 - Comparison of Two Values Using Ternary Operators

Consider the below C# program for comparison of two values using ternary operators.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace HelloWorld
{
    class Program
    {
        static void Main(string[] args)
        {
            int a = 40;
            int b = 50;
            Console.WriteLine((a < b) ? "a's value is less than b" : "b's value is less than a");
            Console.ReadLine();
        }
    }
}

Output:

• In the above program, two variables, a and b, are defined and assigned some values. 
• Their values are compared against each other to find out which is greater using ternary operators. 
• The conditional statement is executed, and the result of the statement is assigned to a variable res. 
• If the conditional statement’s result is true, the second statement after the ‘?’, which is a’s value is more than b, is printed; otherwise, the third statement after the ‘:’  b’s value is less than a is printed.

3 - Nested Ternary Operator

When the second argument or the third argument after ‘?’ or after ‘:’ is a conditional statement again, then the operator is called the nested ternary operator.

For example:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace HelloWorld
{
    class Program
    {
        static void Main(string[] args)
        {
            int a = 10;
            int b = 5;
            Console.WriteLine(a > b ? "a's value is more than b" : a < b ? "a's value is less than b" : a == b ? "C" : "No result");

            Console.ReadLine();
        }
    }
}

Output:

In the above program, two variables, a and b, are defined and assigned some values. 

Their values are compared against each other to find out which is greater or if they are equal using ternary operators in C#.

The conditional statement is executed, and the result of the statement is assigned to a variable res.

If the result of the conditional statement is true, the second statement after the ‘?’ which is again a conditional statement a<b is executed, the result of which is assigned to either a’s value is less than b statement before ‘:’ or another conditional statement a==b is executed which is again a conditional statement. The result of this expression prints a’s value is less than b or No result statements.