std::basic_string<CharT,Traits,Allocator>::at
reference at( size_type pos ); |
(until C++20) | |
constexpr reference at( size_type pos ); |
(since C++20) | |
const_reference at( size_type pos ) const; |
(until C++20) | |
constexpr const_reference at( size_type pos ) const; |
(since C++20) |
Returns a reference to the character at specified location pos. Bounds checking is performed, exception of type std::out_of_range will be thrown on invalid access.
Parameters
| pos | - | position of the character to return |
Return value
Reference to the requested character.
Exceptions
Throws std::out_of_range if pos >= size().
Complexity
Constant.
Example
#include <stdexcept>
#include <iostream>
#include <string>
int main()
{
std::string s("message"); // for capacity
s = "abc";
s.at(2) = 'x'; // ok
std::cout << s << '\n';
std::cout << "string size = " << s.size() << '\n';
std::cout << "string capacity = " << s.capacity() << '\n';
try {
// This will throw since the requested offset is greater than the current size.
s.at(3) = 'x';
}
catch (std::out_of_range const& exc) {
std::cout << exc.what() << '\n';
}
}
Possible output:
abx string size = 3 string capacity = 7 basic_string::at
See also
| accesses the specified character (public member function) |
|
|
(C++17)
|
accesses the specified character with bounds checking (public member function of std::basic_string_view<CharT,Traits>) |
© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
https://en.cppreference.com/w/cpp/string/basic_string/at
