Lesson 6: Strings

At the end of this lesson, you should be able to answer the following:

• How do I get the length (number of characters) of a string?

• How do I join multiple strings together?

• How do I make a template string for string interpolation?

• What is a verbatim string?

Let's have fun with strings!

String Length

Recall that strings represent text values. All strings have a property called Length which returns the number of characters in the string. To get the length, attach .Length to a string value or variable.

// Calling Length directly from a string
Console.WriteLine("12345".Length);

// Calling Length from a string variable
var someString = "abcdef";
Console.WriteLine(someString.Length);

String Concatenation

Declare two string variables, one to hold a first name and one for a last name.

var firstName = "Jane";
var lastName = "Shepard";

We can join two strings together to form a combined string using the + operator. This is called string concatenation.

var firstName = "Jane";
var lastName = "Shepard";

var name = firstName + lastName;
Console.WriteLine(name);

The variable name contains a new string, the value JaneShepard.

But wait! That doesn't look right. It would look better if there was a space in between them.

To do this, we'll need to add a space in one of the variables. We can add it after firstName or before lastName. We could also just add a space string between the two variables.

Add a space string (" ") between the expression firstName + lastName. Remember to use another + to add this new string into the mix!

var firstName = "Jane";
var lastName = "Shepard";

var name = firstName + " " + lastName;
Console.WriteLine(name);

Now our name has a space between the first and last names.

String Interpolation

When we have a lot of strings to join together, it can get convoluted quickly. Instead of joining the strings using +, we could insert our strings into a template string. This is called string interpolation.

String interpolation can provide a more readable syntax.

var firstName = "Jane";
var lastName = "Shepard";

var name = $"{firstName} {lastName}";
Console.WriteLine(name);

The code above is almost the same as the one before it, except that the expression assigned to name is different.

• The string value begins with a $.

• The variables firstName and lastName are inside the string.

• The variables firstName and lastName are wrapped in curly braces {}.

• There is a space separating {firstName} and {lastName}.

The variable name has a template string assigned to it.

We made a template string by putting a $ before the string value. Then we inserted the variables we wanted by wrapping them in curly braces and placing them in their desired positions inside the string.

We want a space between the first name and last name, so there is a space already in the template string.

If we wanted the output to be Shepard, Jane instead, we can change the template string like this:

$"{lastName}, {firstName}"

Replace name with this template string and run the code. The output should be Shepard, Jane.

Verbatim Strings

We can make a string span multiple lines. A verbatim string is a string that keeps the lines and spaces in a string as it is defined.

To make a verbatim string, place the @ character in front of a string value.

var multiLine = @"This string spans 
multiple lines 
    and keeps the spaces too!";
Console.WriteLine(multiLine);

Type the program above in a code box and run it. The string will print in multiple lines, even if we only used one Console.WriteLine() statement.

Question

Why would one use string interpolation over concatenation?

Question

Find the error in this code and fix it. The output should be I came, I saw, I conquered.

var action1 = "I came";
var action2 = "I saw";
var action3 = "I conquered.";

var actions = action1 + ", " + action2 ", " + action3;
Console.WriteLine(actions);

Challenge

Copy the code in the question above and change it to use string interpolation. Replace actions with a template string. The output should be I came, I saw, I conquered.

Challenge

Make a Fill-In-The-Blanks story!

Come up with a story that has 3 or 4 sentences. Replace a word in each sentence with a variable. Declare those variables with initial values and print out the complete story.

Sample story:

var story = @"Three little _________,
They lost their __________,
And they began to ________.";