std::basic_string::at in C++

Returns a reference to the character at the specified location pos. The function automatically checks whether pos is the valid position of a character in the string (i.e., whether pos is less than the string length), throwing an out_of_range exception if it is not.


reference at (size_type pos);
const_reference at (size_type pos) const;
Parameters :
pos - position of the character to return
Return value :
Reference to the requested character
Exceptions :
Throws std::out_of_range if pos >= size().
// CPP program to access a character through
// std::basic_string::at 
#include <stdexcept>
#include <iostream>

int main()
    // String with valid indices from 0 to 2
    std::string str = "abc";

    // Printing size of string
    std::cout << "string size = " << str.size() << '\n';

    // Accessing out of bounds index
    { = 't';
    // If error is generated, it is caught
    catch (std::out_of_range const& error) 
        std::cout << error.what() << '\n';


string size = 3
basic_string::at: __n (which is 4) >= this->size() (which is 3)

This article is contributed by Rohit Thapliyal. If you like GeeksforGeeks and would like to contribute, you can also write an article using or mail your article to See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.

GATE CS Corner    Company Wise Coding Practice

Recommended Posts:

Writing code in comment? Please use, generate link and share the link here.