Reading and Writing to the Console

In the previous article we discussed about the basic structure of a C# program. Today we will see reading and writing operation to the console. We will see a little more interactive sample program than the previous today. Our program will ask the user his/her name and then print a welcome message with the name of the user which he/she just enter.

To write something to the console we have two methods under System namespace, one is Write and the other is WriteLine. Only the difference between these two is, if we use WriteLine then after writing something to the console it will print a new line also but in Write method it will just print something. No new line will be printed here.

For an example if we write in the main method Console.Write(“Hello World ”); then the output should be as follows-

Hello World press any key to continue

The line “press any key to continue” indicates that the program is terminated. Instead of this method if we use Console.WriteLine(“Hello World ”); then the output should be as follows-

Hello World

press any key to continue

Here we can see that the line “press any key to continue” is in a new line. So the method Writeline prints a new line after writing something to the console.

Similarly there are to methods for reading something in the console, one is Read and the other is ReadLine. The Read method read integer type from the console and the Readline method read string type from the console. So if we write Console.ReadLine() then we have to store the returned result in a string type variable so that we can use it later in the program.

Now let’s see the code our sample program. It is as follows-

using System;
class Program
{
   static void Main()
    {
        Console.WriteLine("What is your name?");
        string name = Console.ReadLine();
        Console.WriteLine("Welcome "+ name);
    }
}

Here we can see in the MAIN method first we are printing a message asking the user’s name. Then when our next line of code executed it waits for the user input that is our read operation from the console. When the user enters something and press the Enter button then Console.Readline methos reads what is entered in the console and return it as a string type. Here we store the returned string in a string type variable named name. So what user entered in the console now stored in the variable. Then in the next line we write in the console “Welcome “concatenated with the name of the user. Here we are concatenating two string- One is “Welcome ” and the other is string type variable called name with the “+” sign in the WriteLine method.
There are actually two ways of writing something in the console. They are-
• Concatenation
• Place holder syntax
We already have seen the concatenation method of writing something to the console. Now we will see the place holder syntax in the same program. If we want to use place holder syntax in the same program then the code should be as follows-

using System;
class Program
{
   static void Main()
    {
        Console.WriteLine("What is your name?");
        string name = Console.ReadLine();
        Console.WriteLine("Welcome {0}",name);
    }
}

Here we can see in case of “+” operator we use “{0}” in the string with Welcome. This is called the place holder. When we run the program, the value of the variables that we pass after comma in the WriteLine method replaces the place holder. So if we run this piece of code we will see the same result here.
The place holder syntax is more preferable than the Concatenation process. To see how place holder syntax gives more capability let’s modify the above program. Now we will ask the user to enter his/her first name then after reading the first name we will ask for last name and after reading that we will print the first name and last name separated by a comma with the welcome message. To do that the program should be as follows –

using System;
class Program
{
   static void Main()
    {
        Console.WriteLine("What is your first name?");
        string firstname = Console.ReadLine();
        Console.WriteLine("What is your last name?");
        string lastname = Console.ReadLine();
        Console.WriteLine("Welcome {0},{1}",firstname,lastname);
    }
}

Here in the code we can see there are two place holders and there are two string type variable as well to store the first name and last name of user. When we write the welcome message in WriteLine method we use two placeholder and two variable to replace the place holder. In the same way we can use as many as place holders we required. We just have to surround the number of that place holder with curly braces. That’s why place holder syntax is more preferable than the concatenation method.

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