Dart example program to replace a substring

Introduction :

In this tutorial, we will learn how to replace a part of a string in dart. Dart string class comes with a method called replaceRange, that we can use to replace a part of the string with a different string. In this tutorial, we will learn how to use replaceRange with an example in Dart.

Definition :

replaceRange is defined as below :

String replaceRange (
int start,
int end,
String str

It replaces the string from index start to end with different string str. It returns one new string i.e. the modified string.

The start and end indices should be in a valid range. If the value of end is null, it will take the default length length.

Example :

import "dart:core";

void main() {
  final givenString = "hello world";
  final newString = givenString.replaceRange(0, 3, "1");


It will print the below output :

1lo world

dart replacerange example

As you can see in the above example, it replaced the string part from index 0 to 3 with 1.

Try to run the above example with different indices and different strings to learn more about how replaceRange works.

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