Question

I have a confusion while dealing with char pointers. Please have a look at following code:

class Person
{
    char* pname;
public:
    Person(char* name)
    {
        //I want to initialize 'pname' with the person's name. So, I am trying to
        //achieve the same with different scenario's

        //Case I:   
        strcpy(pname, name); // As expected, system crash.

        //Case II: 
        // suppose the input is "ABCD",  so trying to create 4+1 char space
        // 1st 4 for holding ABCD and 1 for '\0'.
        pname = (char*) malloc(sizeof(char) * (strlen(name)+1) );
        strcpy(pname, name);

        // Case III: 
        pname = (char*) malloc(sizeof(char));
        strcpy(pname, name);
    }

    void display()
    {
        cout<<pname<<endl;
    }
};

void main()
{
    Person obj("ABCD");
    obj.display(); 
}

For Case I:
As expected, system crash.

Output for Case II:

ABCD

Output for Case III:

ABCD

So, I am not sure why Case II & III are producing the same output !!!!…..
How I should initialize a char pointer in a class?

Answer 1

The third case invokes Undefined Behavior and so anything might happen in that case.
You are writing beyond the bounds of allocated memory in this case which may or maynot crash but is a UB.

How to do this the right way in C++?
By not using char * at all!
Just simply use std::string.

Note that std::string provides you with c_str() function which gets you the underlying character string. Unless, You are bothered about passing ownership of a char * to a c-style api you should always use std::string in c++.