Summary - Strings

Combine interpolation, length and contains to write a business card.

Summary - Strings

In this group you learned String creation, interpolation, .length, .toUpperCase(), .substring(), .contains() and .indexOf(). Now we will combine them to print a business card.

The card will show the name, the length and the presence of the @ sign. The goal is to use several String tools together in one program. Each piece is small; together they give a meaningful output.

Information with length

On a business card the number of letters in the name can be informative. With name.length we take the character count, assign it to a new variable and print it with interpolation. Example: var len = name.length; and print("Length: $len");.

The same could be done in one line with ${name.length}; but assigning to len lets us reuse the value later. Building the program step by step makes debugging easier.

Exercise Print a business card

Declare a String variable name with the value "Alex". Declare a variable len and assign the result of name.length to it. Then print with print("Name: $name, length: $len");. The output on a single line must be Name: Alex, length: 4.

Show example solution

String name = "Alex";
var len = name.length;
print("Name: $name, length: $len");

Test yourself

Complete the card line

String name = "Alex";
print("Name: ____");

Show answer

String name = "Alex";
print("Name: $name");

How do you check if an email has @?
```
String email = "a@b.com";
```
- email.length("@")
- email.contains("@")
- email.substring("@")
- email.toUpperCase("@")
Show answer

email.contains("@") — contains("@") returns a bool for the presence of @.

Next lesson: The if statement

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