我们可以将 const char* 分配给 cpp 中的字符串吗？

Question

Although my compiler doesn't throw an error while assigning const char* to a string, I am wondering if this assignment is really valid and will not throw some unexpected result

string name;
const char* name2 = "ABCD";

name = name2;

Answer 1

You absolutely can.

std::string was meant to replace the tedious and error-prone C strings const char* so for it to be a good replacement/successor it'd need backwards compatibility with const char* which it does.

name = name2; calls operator= so if we check basic_string s overloads for this operator we can see (3):

basic_string& operator=( const CharT* s );

_{Here CharT is of the type char so you get const char*}

Which does what you'd expect it to do, it copies over the contents the const char* is pointing to, to the internal buffer of std::string :

Replaces the contents with those of null-terminated character string pointed to by s as if by assign(s, Traits::length(s)) .

In order to go the other route though, from a std::string to a const char* , you'd need to call its method c_str() on the std::string object.

Answer 2

I am wondering if this assignment is really valid

Yes it's valid:

string name;
const char *name2 = "ABCD";
name = name2;

Note name = name2 calls std::string assignment operator, after which the two variables are totally independent, ie you are free to change name , while name2 remains const (aka literal string).