C++ 将 const char * 转换为 std::string
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Converting a const char * to std::string
提问by Justin Fletcher
I've got a const char *returned from a processing function, and I'd like to convert/assign it to an instance of std::stringfor further manipulation. This seems like it should be straight-forward, but I've not been able to find any documentation showing how it should be done. Obviously, I'm missing something. Insights appreciated.
我有const char *一个处理函数的返回值，我想将它转换/分配给一个实例以std::string进行进一步操作。这似乎应该是直截了当的，但是我找不到任何说明应该如何完成的文档。显然，我错过了一些东西。见解赞赏。
回答by Ivaylo Strandjev
std::stringhas a constructor fromconst char *.This means that it is legal to write:
std::string有一个来自 的构造函数const char *。这意味着这样写是合法的：
const char* str="hello";
std::string s = str;
回答by Ed Heal
Try
尝试
const char * s = "hello";
std::string str(s);
will do the trick.
会做的伎俩。
回答by Fred Larson
std::stringhas a constructor that converts const char*implicitly. In most cases, you need to do nothing. Just pass a const char*where a std::stringis accepted and it will work.
std::string有一个const char*隐式转换的构造函数。在大多数情况下，您什么都不用做。只需通过一个const char*其中一个std::string被接受，它会工作。
回答by Vlad from Moscow
There are three possibilities. You can use a constructor, an assignment operator or member function assign(if do not take into account member function insertthough it is also can be used:) )`
有三种可能。您可以使用构造函数、赋值运算符或成员函数assign（如果不考虑成员函数，insert尽管它也可以使用:)）`
For example
例如
#include <iostream>
#include <string>
const char * f() { return "Hello Fletch"; }
int main()
{
std::string s1 = f();
std::string s2;
s2 = f();
std::string s3;
s3.assign( f() );
std::cout << s1 << std::endl;
std::cout << s2 << std::endl;
std::cout << s3 << std::endl;
}
回答by Appleshell
You've got a lot of options:
你有很多选择：
const char* dosth() { return "hey"; }
string s1 = dosth();
string s2 (dosth());
string s3 {dosth()};
auto s4 = (string)dosth();
Note that s3and s4are C++11 features, if you should still work with an old or non-compliant compiler you would have to work with one of the other options.
请注意，s3和s4是 C++11 功能，如果您仍应使用旧的或不兼容的编译器，则必须使用其他选项之一。
