Basic String Formatting

String Formatting refers to the process of constructing and customizing textual output. It involves inserting variables and values into a predefined text template. It is useful for creating readable and structured text representations.

We can output text and a variable value using an already known method (the + operator):

main


              12345678910111213
            
using System;

namespace ConsoleApp
{
    internal class Program
    {
        static void Main(string[] args)
        {
			int number = 10;
			Console.WriteLine("The value is: " + number);
        }
    }
}

However there are better and more suitable methods for string formatting which can also handle complex cases. The first method is by using the placeholder syntax. To understand this syntax we will use the Console.WriteLine method:

main


              123456789101112131415
            
using System;

namespace ConsoleApp
{
    internal class Program
    {
        static void Main(string[] args)
        {
			int val1 = 10;
			int val2 = 20;
			int val3 = 30;
			Console.WriteLine("The values are: {0}, {1} and {2}", val1, val2, val3);
        }
    }
}

In the above code we insert placeholders in the string where values are to be inserted. The syntax of a placeholder is a number (index) enclosed in curly brackets ({index}) and the value index starts from 0. When the output string is generated, the placeholders are filled with the corresponding values that are passed as additional arguments to the Console.WriteLine method.

The following diagram illustrates the process in an easier to understand way:

Note
Arguments are the values we pass into a function or command. For-example, in Console.WriteLine("Value: {0}", 100);, the terms "Value: {0}" and 100 are values.

There is another much simpler method of formatting strings. We can use the $ character to indicate that a string is a formatted string and directly insert values inside it using the curly brackets ({}):

Using this syntax, we can also generate and store formatted strings into string variables:

main


              12345678910111213141516
            
using System;

namespace ConsoleApp
{
    internal class Program
    {
        static void Main(string[] args)
        {
			int val1 = 10;
			int val2 = 20;
			int val3 = 30;
			string text = $"The values are: {val1}, {val2} and {val3}";
			Console.WriteLine(text);
        }
    }
}

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Seção 2. Capítulo 8