Difference between revisions of "cpp/string/basic string/at"
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< cpp | string | basic string
m (Update links.) |
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===Complexity=== | ===Complexity=== | ||
Constant | Constant | ||
| + | |||
| + | ===Example=== | ||
| + | {{ | ||
| + | example | ||
| + | | code= | ||
| + | #include <stdexcept> | ||
| + | #include <iostream> | ||
| + | |||
| + | 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 { | ||
| + | // throw, even if capacity allowed to access element | ||
| + | s.at(3) = 'x'; | ||
| + | } | ||
| + | catch (std::out_of_range& exc) { | ||
| + | std::cout << exc.what() << '\n'; | ||
| + | } | ||
| + | } | ||
| + | | output= | ||
| + | abx | ||
| + | string size = 3 | ||
| + | string capacity = 7 | ||
| + | basic_string::at | ||
| + | }} | ||
===See also=== | ===See also=== | ||
Revision as of 07:31, 7 September 2013
| reference at( size_type pos ); |
||
| const_reference at( size_type pos ) const; |
||
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.
Contents |
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> 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 { // throw, even if capacity allowed to access element s.at(3) = 'x'; } catch (std::out_of_range& exc) { std::cout << exc.what() << '\n'; } }
Output:
abx string size = 3 string capacity = 7 basic_string::at
See also
| accesses the specified character (public member function) |
