Chapter 4.1. More Complex Conditions

In the current chapter, we are going to examine the nested conditional statements in the C# language, by which our program can contain conditions that contain other nested conditional statements. We call them "nested", because we put an if condition into another if condition. We are going to examine the more complex logical conditions through proper examples.

Video: Chapter Overview

Watch this video to see what you will learn in this chapter: https://youtu.be/qvbVrKXxsu0.

Introduction to Complex Conditions by Examples

Conditional statements can be nested, i.e. we can put if-else inside another if-else statement. Conditions in the if constructions can be complex, e.g. use logical "AND" or logical "OR". Example:

var a = decimal.Parse(Console.ReadLine());
var b = decimal.Parse(Console.ReadLine());
if (a > 0 && b > 0 && a <= 100 && b <= 100)
{
    if (a * b >= 5000)
        Console.WriteLine($"Large size: {a*b}");
    else if (a * b > 1000 && a * b < 5000)
        Console.WriteLine($"Middle size: {a * b}");
    else
        Console.WriteLine($"Small size: {a * b}");
}
else
    Console.WriteLine($"Invalid size (a={a}, b={b})");

Run the above code example: https://repl.it/@nakov/nested-if-else-conditions-csharp.

The above code performs a series of checks using nested if-else conditional statements and logical operators like && (logical AND) to check the input data for the following 4 cases:

• Size out of range (one of the sides is negative or bigger than 100).
• Large size (area >= 5000).
• Middle size (1000 < area < 5000)
• Small size (area <= 1000)

Let's explain in greater detail how to use complex and nested if-else conditions in C#.