Question

I am C++ beginner. I have a code as below

#include <iostream>
#include <string>
#include <iomanip>

using namespace std;
int main()
{
   char sym[] = "Audi.Despo";
   //string sym ("Audi.Despo");
    string rs(sym);
    //cout << rs << endl;
    rs = string(sym,4);

 cout << rs;

    return 0;
}

If the variable sym is a char array the final output of the string variable is
Audi

but if the same variable sym is a string the final output is .Despo (the suffix is printed)

Whats the explanation.

Looks like the line

rs = string(sym,4);

changes its behaviour if its input is a char [] or a string.

Answer 1

That’s just the different implementations of two of the constructor overloads:

string ( const string& str, size_t pos, size_t n = npos );

Content is initialized to a copy of a substring of str. The substring is the portion of str that begins at the character position pos and takes up to n characters (it takes less than n if the end of str is reached before).

string ( const char * s, size_t n );

Content is initialized to a copy of the string formed by the first n characters in the array of characters pointed by s.