Flutter & Dart: Convert a String/Integer to Hex

This practical shows you how to convert a number (integer) or a string to a hexadecimal value in Dart (and Flutter as well).

Turn a Number into Hex

Calling the toRadixString() method with a radix of 16 will produce a hex string from an input integer.

Code example:

// KindaCode.com
import 'package:flutter/foundation.dart';

void main() {
  int number = 20232024;
  String hexString = number.toRadixString(16);
  debugPrint(hexString);
}

Output:

134b758

Convert a String to Hex

The main idea here is to use the runes property to get a list of Unicode code points for each character in the input string. Then, call the map() function to convert each code point to a hexadecimal string using toRadixString(16).

Example:

// KindaCode.com
import 'package:flutter/foundation.dart';

void main() {
  String input = "Welcome to KindaCode.com!";
  List<int> charCodes = input.runes.toList();
  String hexString = charCodes.map((code) => code.toRadixString(16)).join('');
  debugPrint(hexString);
}

Output:

57656c636f6d6520746f204b696e6461436f64652e636f6d21

That’s it. Further reading:

• Flutter & Dart: Convert Strings to Binary
• Flutter & Hive Database: CRUD Example
• Flutter & SQLite: CRUD Example
• Flutter Stream.periodic: Tutorial & Example
• How to Create a Countdown Timer in Flutter

You can also tour around our Flutter topic page or Dart topic page for the most recent tutorials and examples.