table of contents
std::basic_string::at(3) | C++ Standard Libary | std::basic_string::at(3) |
NAME¶
std::basic_string::at - std::basic_string::at
Synopsis¶
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¶
// Run this code
#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¶
operator[] accesses the specified character
(public member function)
at accesses the specified character with bounds checking
(C++17) (public member function of
std::basic_string_view<CharT,Traits>)
2022.07.31 | http://cppreference.com |