将const char *分配给字符串是否有危险？

Question

I am basically assigning a const char* value to a string. I am checking for a condition and setting the string to be empty as a default value.

In the parameterised constructor I am setting the string to be empty as follows

ClassName:: ClassName(X x, string name):X(x), name(){}

I set the string empty once I am done using it as

name="";

Is the above approach of initialisation correct?

Also is there any risk of assigning a const char* to a string?

const char* diag;
string name;

name= diag;

Answer 1

The class std::string has corresponding constructors and assignment operators for objects of type char * . The only problem that can arise relative to the objects of this type is when the initializer is a null pointer.

Take into account that if there is declared a variable like this

const char *name = "";

then name is not a null pointer. It is a pointer to the first character (character '\\0' ) of an array of type const char[1] that corresponds to the "empty" string literal and that has the static storage duration.

If you write for example

std::strig s( name );

or

std::string s = name;

then you will get an empty object s of type std::string becsuse there is nothing to copy from the "empty" string literal.

Thus it does not make sense to declare objects of type std::string such a way. It is enough to write

std::string s;

Answer 2

在您的示例中没有问题，但是通常您需要知道const char *指向的字符数组以空const char *结尾，否则std :: string构造函数将继续读取内存，直到结束为止。数组。