String in Dart/Flutter — Things you should know

String is an important data type in almost programming languages (if not all). Dart is not an exception. In this post, I will show you a several things that you may (or may not) know about String in Dart/Flutter.

1. String literals can be wrapped in single quotes or double quotes.

// Both are accepted in Dart
const singleQuoteString = 'Hello Coflutter';
const doubleQuoteString = "Hello Coflutter";

?? It is recommended that you make it consistently, choose one style and use it throughout your code.

2. If you use pedantic as your linter, single quotes is preferred.

// Warning with pedantic
const s1 = "Hello Coflutter"; // Warning: Only use double quotes for strings containing single quotes.
const s2 = "Hello. I'm Coflutter"; // OK

?? You can find the rule here.

3. Use a backslash ( \ ) to escape special characters.

print("I'm Coflutter");
print("I\'m Coflutter");
print("I\'m \"Coflutter\"");
print('Path: C:\\Program Files\\Coflutter');

utput
I'm Coflutter
I'm Coflutter
I'm "Coflutter"
Path: C:\Program Files\Coflutter

4. “Raw” string (r before string) can be used to escape special character too.

// "Raw" string
print(r'Path: C:\Program Files\Coflutter');
print(r'I have $100 USD');

/ Output
Path: C:\Program Files\Coflutter
I have $100 USD

5. Triple quotes can be used to represent multiple lines string (instead of using “new line” character (\n)).

// Multiple lines string
print(
      '''This is a multiple line string,
      created by Coflutter
      '''
);

6. Override toString( ) method in your object to have beautiful output when print( ).

?? Find details and example here.

7. String supports padding methods: paddingLeft( ) and paddingRight( ).

?? Find details and example here.

8. String multiplication is supported in Dart. But the string must be placed before the multiply operator (Permutation does not work).

const fire = '??';
  for (var i = 0; i <= 3; i++) {
    // final output = i * fire;
    // -> Error: The argument type 'String' can't be assigned to the parameter type 'num'.

    final output = fire * i;
    print(output);
}

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9. String interpolation.

?? Interesting facts about String Interpolation.

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