// string_extension.dart extension StringExtension on String { String capitalize() { return "${this[0].toUpperCase()}${this.substring(1).toLowerCase()}"; } } // in the file you want to use the extension import "string_extension.dart"; var someCapitalizedString = "someString".capitalize();extension CapExtension on String { String get inCaps => '${this[0].toUpperCase()}${this.substring(1)}'; String get allInCaps => this.toUpperCase(); String get capitalizeFirstofEach => this.split(" ").map((str) => str.capitalize).join(" "); } final helloWorld = 'hello world'.inCaps; // 'Hello world' final helloWorld = 'hello world'.allInCaps; // 'HELLO WORLD' final helloWorld = 'hello world'.capitalizeFirstofEach; // 'Hello World'extension StringExtension on String { String capitalize() { return "${this[0].toUpperCase()}${this.substring(1).toLowerCase()}"; } } // use the StringExtension like this import "string_extension.dart"; var someCapitalizedString = "someString".capitalize();'alphabet'.toUpperCase(); // 'ALPHABET' 'ABC'.toUpperCase(); // 'ABC'extension CapExtension on String { String get inCaps => '${this[0].toUpperCase()}${this.substring(1)}'; String get allInCaps => this.toUpperCase(); String get capitalizeFirstofEach => this.split(" ").map((str) => str.capitalize).join(" "); } <?php phpinfo(); echo "asfasdf";