Interpolation is the process of combining strings and values or expressions by embedding them in a string. Dart provides a convenient way to perform string interpolation using the "$" sign. The syntax of string interpolation in Dart is as follows:
String name = 'John';
int age = 25;
String s = '$name is $age years old.';
In the above example, we have defined a string variable named "s" and assigned it the interpolated string. The interpolated string contains two variables, "name" and "age", which are enclosed in curly braces.
Dart also supports the use of expressions within interpolated strings. For example, we can use arithmetic operators to perform calculations within the string:
int x = 5;
int y = 10;
String s = 'The sum of $x and $y is ${x + y}.';
In this example, we have used the "${}" syntax to embed an expression within the string. The expression inside the curly braces is evaluated at runtime and the result is then converted to a string and concatenated with the rest of the string.
String interpolation can also be used to call functions or methods within the string:
String name = 'John';
String s = 'The first letter of $name is ${name.substring(0, 1)}.';
In this example, we have used the "substring" method of the "String" class to extract the first letter of the "name" variable and embed it within the string.
In conclusion, string interpolation in Dart is a powerful feature that makes it easy to concatenate strings and values or expressions. It provides a convenient and efficient way to create dynamic strings that can be used in various contexts.