std::basic_string::substr
性病：基本[医]字符串：Substr
| basic_string substr( size_type pos = 0, size_type count = npos ) const; | | |
|---|
返回一个子字符串。[pos, pos+count)如果请求的子字符串扩展到字符串的末尾，或者count == npos，返回的子字符串是[pos,size())...
参数
| pos | - | position of the first character to include |
|---|---|---|
| count | - | length of the substring |
返回值
包含子字符串的字符串。[pos, pos+count)...
例外
std::out_of_range如果pos >size()...
复杂性
线性在count...
例
二次
#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";
}
}
二次
产出：
二次
abcdefghij
567
hij
pos exceeds string size
二次
另见
| copy | copies characters (public member function) |
|---|---|
| sizelength | returns the number of characters (public member function) |
| find | find characters in the string (public member function) |
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