std::basic_stringstream<CharT,Traits,Allocator>::str
来自cppreference.com
< cpp | io | basic stringstream
| (1) | ||
| std::basic_string<CharT,Traits,Allocator> str() const; |
(C++20 前) | |
| std::basic_string<CharT,Traits,Allocator> str() const&; |
(C++20 起) | |
| template<class SAlloc> std::basic_string<CharT,Traits,SAlloc> str( const SAlloc& a ) const; |
(2) | (C++20 起) |
| std::basic_string<CharT,Traits,Allocator> str() &&; |
(3) | (C++20 起) |
| void str( const std::basic_string<CharT,Traits,Allocator>& s ); |
(4) | |
| template<class SAlloc> void str( const std::basic_string<CharT,Traits, SAlloc>& s ); |
(5) | (C++20 起) |
| void str( std::basic_string<CharT,Traits,Allocator>&& s ); |
(6) | (C++20 起) |
管理底层字符串对象的内容。
1) 返回底层字符串的副本。等价于 return rdbuf()->str(); 。
2) 返回底层字符串的副本，以
a 为分配器。等价于 return rdbuf()->str(a); 。3) 返回从底层字符串移动构造的字符串。等价于 return std::move(*rdbuf()).str(); 。
4-5) 替换底层字符串。等价于 rdbuf()->str(s); 。
6) 替换底层字符串。等价于 rdbuf()->str(std::move(s)); 。
参数
| s | - | 底层字符串的新内容 |
| a | - | 用于构造返回的字符串的分配器 |
返回值
1-2) 底层字符串对象的副本。
3) 从底层字符串对象移动构造的字符串。
4-6) （无）
注解
str 所返回的底层字符串副本是将于表达式结尾析构的临时对象，故在 str() 的结果上直接调用 c_str() （例如 auto *ptr = out.str().c_str(); 中）导致悬垂指针。
示例
运行此代码
#include <sstream> #include <iostream> int main() { int n; std::istringstream in; // 亦可使用 in("1 2") in.str("1 2"); in >> n; std::cout << "after reading the first int from \"1 2\", the int is " << n << ", str() = \"" << in.str() << "\"\n"; std::ostringstream out("1 2"); out << 3; std::cout << "after writing the int '3' to output stream \"1 2\"" << ", str() = \"" << out.str() << "\"\n"; std::ostringstream ate("1 2", std::ios_base::ate); ate << 3; std::cout << "after writing the int '3' to append stream \"1 2\"" << ", str() = \"" << ate.str() << "\"\n"; }
输出：
after reading the first int from "1 2", the int is 1, str() = "1 2" after writing the int '3' to output stream "1 2", str() = "3 2" after writing the int '3' to append stream "1 2", str() = "1 23"
参阅
| 替换或获得关联字符串的副本 ( std::basic_stringbuf<CharT,Traits,Allocator> 的公开成员函数) |
