String Interpolation

Part of the Fundamentals section of Coddy's C# journey — lesson 32 of 69.

So far we have learned how to print simple strings, but sometimes we need to insert variable values into the string.

For example:

int age = 10;
System.Console.WriteLine("His age is: age");

This will print "His age is: age" instead of "His age is: 10"

To solve this, we will use string interpolation:

int age = 30;
string name = "Alice";
double balance = 1500.75;

System.Console.WriteLine($"Name: {name}, Age: {age}, Balance: {balance}");

$ indicates that the string is an interpolated string.
{} are placeholders for variables.

Another way to combine strings with variables is with the plus + operator:

System.Console.Write("Name: " + name + " Age: " +  age + " Balance: " + balance);

Challenge

Beginner

You are given a code that stores a random string as input to a variable named rnd.

Print to the console "The input is: " and the random string that is inside the variable rnd, using string interpolation.

Check the test cases for examples!

Try it yourself

using System;

public class Program {
    public static void Main(string[] args) {
        string rnd = Console.ReadLine();
        
        // Write your code below
        
    }
}

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in Fundamentals

1Introduction

C#Hello World!Comments Basic Program Structure

4Operators Part 1

Arithmetic Operators Modulo Operator Increment/Decrement Post Increment/Decrement Arithmetic Shortcuts

7Basic IO

Basic OutputString InterpolationReading Input Parse Recap - Till 120 Recap - True or False

10Methods (Functions)

Declaring Methods Method Parameters Return Types Optional Parameters Recap - Validation Function Void Methods

13Iterating Over Collections

Using For Loop Foreach Loop Common Array Operations

2Variables Part 1

Numbers Char String Boolean Type Declaration

5Operators Part 2

Comparison Operators Logical Operators Part 1 Logical Operators Part 2 Recap - Simple Logic Logical Operators Part 3

8Calculator App

Welcome Message Getting Numbers

Basic Operations

Formatted Output

11Arrays Basics

Declaring Arrays Accessing Elements Modifying Arrays Array Methods Recap - Product Array Edit Recap - Reversed Array

14Final Challenges

Number Pattern Pattern Finder Student Grade Calculator

3Variables Part 2

Var Constants Naming Conventions Recap - Initialize Variables Type Casting

6Decision Making

If Statement If - Else Switch Statement Ternary Operator Recap - If Else Nested If - Else

9Loops

For Loop While Loop Do While Loop Break Continue Nested Loop Infinite Loop Recap - Dynamic Input

12String Operations

String Methods Part 1 String Methods Part 2 String Formatting