Question about asteriks and string concatenation in C++

Question

So I am currently going through Accelerated C++ course on udemy by Jeremy Siek and I was on that tutorial which he is mentioning string concatenation and in one part he gave task to print something (WITHOUT USING NESTED LOOPS) like this:

OUTPUT:

*
**
***
****

(- So I know about for loops from earlier and I am not completely new to C++ programming, but I am just complementing knowledge from earlier and I know that this problem can be solved with nested for loops. But THIS IS NOT MY QUESTION, KEEP READING, BECAUSE I HAVE TO MAKE INTRO INTO MY QUESTION)

Before he made program which is source code like this (WHICH I COMPLETE UNDERSTAND)

int main()
{
cout << "Please enter your name:";
string name;
cin>>name;

string greeting="Hello, " + name + "!";
string spaces(greeting.size(), ' ');
string stars(greeting.size(), '*');

cout << "**" stars << "**" << endl;
     << "* "<< spaces << " *"<< endl;
     << "* "<< greeting << " *"<< endl; 
     << "* "<< spaces << " *" <<endl;
     << "**" stars << "**" << endl;  

return 0;

} 

Now, about my question: I was trying to do that task he gave, and I came up with something like this:

#include<iostream>
#include<string>
using namespace std;

int main()
{
  string star="*";
  int br=1;

  cout<<star<<endl;
  while(br<4)
  {
    br+=1;
    string (newstar.size(br, '*') );

    cout<<newstar<<endl;
  } 



  return 0;
}

Now, that program resulted error because of string (newstar.size(br, '*') ); which I don't understand why is that wrong and why is string newstar(br, '*'); correct without.size and without ()?

Answer 1

The error is

prog.cc: In function 'int main()':
prog.cc:14:13: error: 'newstar' was not declared in this scope
     string (newstar.size(br, '*') );
             ^~~~~~~
prog.cc:14:13: note: suggested alternative: 'star'
     string (newstar.size(br, '*') );
             ^~~~~~~
             star

Because you did not declare newstar . The compiler already stops there, but there is more wrong: std::string::size takes no paramters and it is not clear what you expect from writing string ( some_number); .

As I dont really understand the logic of your code I cannot offer you a complete fix, but I can give a hint. This:

std::cout << std::string(4,'*');

constructs a std::string consisting of 4 copies of the character * and prints that on the console.

Answer 2

I think your intention was to have:

 string newstar(br, '*');

istead of:

string (newstar.size(br, '*') );

also maybe increment br after that line, and you could remove 'cout << star << endl;'

See the fill constructor: http://www.cplusplus.com/reference/string/string/string/