Type ‘string’ is not a subtype of type ‘int’ of ‘index’

The error message “type ‘string’ is not a subtype of type ‘int’ of ‘index'” typically occurs when trying to access an element in an array or list using a string instead of an integer as the index. In programming, indices are used to access specific elements in an ordered collection of data, such as arrays or lists.

Here’s an example to illustrate this error:

    List numbers = [1, 2, 3, 4, 5];
    String index = '3';
    int element = numbers[index]; // Error: type 'string' is not a subtype of type 'int' of 'index'
  

In the above example, the index variable is declared as a string, whereas it should be an integer value to access an element in the numbers list. This causes a type mismatch error because the index expects an integer, not a string.

To fix this error, ensure that you’re using an integer value as the index. Here’s the corrected example:

    List numbers = [1, 2, 3, 4, 5];
    int index = 3;
    int element = numbers[index]; // Correct: accessing the element at index 3 (value 4)
  

In the corrected example, the index variable is of type int, matching the expected type for an index. Now, the element variable can access the value 4, which is at index 3 in the numbers list.