# Array Indexing To get the element of an array at a specific index, the indexing syntax can be used: The array is followed by an opening square bracket `[`, the indexing value, and ends with a closing square bracket `]`. Indexes start at 0 for the first element in the array. Accessing an element which is out of bounds results in a fatal error at run-time and aborts the program. ``` // Declare an array of integers. let numbers = [42, 23] // Get the first number of the array. // numbers[0] // is `42` // Get the second number of the array. // numbers[1] // is `23` // Run-time error: Index 2 is out of bounds, the program aborts. // numbers[2] ``` ``` // Declare an array of arrays of integers, i.e. the type is `[[Int]]`. let arrays = [[1, 2], [3, 4]] // Get the first number of the second array. // arrays[1][0] // is `3` ``` To set an element of an array at a specific index, the indexing syntax can be used as well. ``` // Declare an array of integers. let numbers = [42, 23] // Change the second number in the array. // // NOTE: The declaration `numbers` is constant, which means that // the *name* is constant, not the *value* – the value, i.e. the array, // is mutable and can be changed. // numbers[1] = 2 // `numbers` is `[42, 2]` ``` --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://max-daunarovich.gitbook.io/flow-network/introduction/values-and-types/arrays/array-indexing.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.