std::basic_string<CharT,Traits,Allocator>::substr
From cppreference.com
< cpp | string | basic string
| basic_string substr( size_type pos = 0, size_type count = npos ) const; |
||
Returns a substring [pos, pos+count). If the requested substring extends past the end of the string, or if count == npos, the returned substring is [pos, size()).
Parameters
| pos | - | position of the first character to include |
| count | - | length of the substring |
Return value
String containing the substring [pos, pos+count).
Exceptions
std::out_of_range if pos > size()
Complexity
Linear in count
Notes
The returned string is constructed as if by basic_string(data()+pos, count), which implies that the returned string's allocator will be default-constructed — the new allocator will not be a copy of this->get_allocator().
Example
Run this code
#include <string> #include <iostream> int main() { std::string a = "0123456789abcdefghij"; // count is npos, returns [pos, size()) std::string sub1 = a.substr(10); std::cout << sub1 << '\n'; // both pos and pos+count are within bounds, returns [pos, pos+count) std::string sub2 = a.substr(5, 3); std::cout << sub2 << '\n'; // pos is within bounds, pos+count is not, returns [pos, size()) std::string sub4 = a.substr(a.size()-3, 50); std::cout << sub4 << '\n'; try { // pos is out of bounds, throws std::string sub5 = a.substr(a.size()+3, 50); std::cout << sub5 << '\n'; } catch(const std::out_of_range& e) { std::cout << "pos exceeds string size\n"; } }
Output:
abcdefghij 567 hij pos exceeds string size
See also
| copies characters (public member function) | |
| returns the number of characters (public member function) | |
| find characters in the string (public member function) |