Is changing the std::string value through it's address is valid?-CodePudding

I was wondering if we can modify std::string value through a pointer to it. Please consider the following example.

#include <iostream>

void func(std::string *ptr) {
    *ptr = "modified_string_in_func";
}
int main()
{
    std::string str = "Original string";
    func(&str);
    std::cout << "str = " << str << std::endl;
    return 0;
}

I tried GCC, Clang & Visual C . All are modifying the string valirable str without any warning or error but I'm not very sure if it's legal to do so.

Please clarify.

CodePudding user response：

That is legal.

You are assigning a new value to the string but are using a pointer to refer to the original string; this is no more illegal then not using a pointer to refer to the original string i.e.

std::string foo = "foo";
foo = "bar";

// is pretty much the same thing as

std::string* foo_ptr = &foo;
*foo_ptr = "bar";

// which is what you are doing.