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How to convert Integer to String or String to Integer in Dart or Flutter | Dart By Example


parse String to or from Integer in Dart

This tutorial shows multiple ways to convert integer to String in Dart or Flutter programming language

The string is a string of numbers enclosed in double quotes An integer is a primitive type of a number

Both represent different types, Automatic conversions are not possible. So, We have to manually Convert String into Int or Int to String with examples

It is easy to parse String to Int in Dart with inbuilt methods

How to parse String to Integer in Dart programming example

There are multiple ways we can do the conversion.

  • use parseInt method in Integer class

integer class provides static parse() method, takes an input string, and converts into int type.

Syntax:

int parse(String str, {int? radix})

Argument is a string of a number, if the string contains non-numeric value, It throws Uncaught Error: FormatException: Radix is an optional parameter and values are 10(default convert to decimal),8,2

Here is an example

void main() {
  var str='123';
  var number = int.parse(str);
  print(number == 123); // true
  print(number.runtimeType); // int

}

parse method throws an error for invalid string of numbers such as non-numeric characters and null.

The below parse method throws Uncaught Error: FormatException: abc

void main() {
  var str='abc';
  var number = int.parse(str);
  print(number == 123); // true
  print(number.runtimeType); // int

}
  • tryParse method in int

    tryParse in the Integer class is advanced to the parse method.

    It handles runtime exceptions and returns a null if you passed a string of non-numeric invalid numbers.

void main() {
  var str='abc';
  var number = int.tryParse(str);
  print(number); // null
  print(number.runtimeType); // Null
}

How to Convert Int to String in Dart with example?

There are multiple ways to convert integer to String in dart.

  • toString()

  • toRadixString();

  • Append string with interpolation syntax

  • toString() method

Every class in dart provides the toString() method.

Integer method provides this method and return string version of a number.

void main() {
  int number = 1;
  String str = number.toString();
  print(str); // 1
  print(str.runtimeType);// String
}
  • toRadixString() method

Syntax:

int toRadixString(int radix)

This method takes radix values such as 16 for hexadecimal, 8 for octal number, 10 default for decimal numbers.

Here is an example

void main() {
  int number = 12;
  String str = number.toRadixString(10);
  print(str); //12 
  print(str.runtimeType); //String
  assert(str is String); // true
}
  • append a string with interpolation syntax

String interpolation (${}) enclosed in single or double quotes You can append strings or plain numbers with interpolation syntax.

Here is an example

void main() {
  int number = 45;
  String str = '${number}';
  print(str); // 45 
  print(str.runtimeType);// String
  assert(str is String); // true
}

Conclusion

To summarize, Learned how to convert string to integer vice versa in Dart language with examples

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