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array at() function in C++ STL
An array is a collection of elements of the same data type stored in continuous memory locations.
In c++ standard library (STL) there are a lot of methods to support the functioning of the array. One of them is an array at() method.
The array at() method is used to return the reference of the element at a specific index value.
Syntax
The general syntax for array at() function is
array_name.at(i);
Parameters
The function accepts a single parameter which I the index of the element which is to be accessed using the function.
Returns
The function returns the element whose index is passed at the time of calling it. If any invalid index value is passed the function throws out_of_range exception.
Example
Program To Demonstrate The Working Of Array::At() Function −
#include <bits/stdc++.h>
using namespace std;
int main(){
array<float, 4> arr = { 12.1, 67.3, 45.0, 89.1 };
cout << "The element at index 1 is " << arr.at(1) << endl;
return 0;
}Output
The element at index 1 is 67.3
Example
Program To Illustrate Error When Index Value Is Greater Than Array Length −
#include <bits/stdc++.h>
using namespace std;
int main(){
array<float, 4> arr = { 12.1, 67.3, 45.0, 89.1 };
cout << "The element at index 1 is " << arr.at(8) << endl;
return 0;
}Output
terminate called after throwing an instance of 'std::out_of_range' what(): array::at: __n (which is 8) >= _Nm (which is 4) The element at index 1 is Aborted
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