While() Loop to create a border of asterisks around text? - c++

Question

Okay, I'm new at programming and decided to jump into this book called Accelerated C++. I'm only on the second chapter and I tried following the exercise, which is to create a program that asks for your name and then output it with a frame around it and padding.
When I execute it, it doesn't seem to be moving onto the next row. I'm guessing it's to do with my while() loop but I'm too dumb to figure out what it is exactly
// ask for a person's name, and greet the person
#include <iostream>
#include <string>
using std::cout;
using std::cin;
using std::string;
int main()
{
// fetch name
cout << "Please enter your first name: ";
string name;
cin >> name;
// message
const string greeting = "Hello, " + name + "!";
// padding
const int pad = 1;
//desired rows/columns
const int rows = pad * 2 + 3;
const string::size_type cols = greeting.size() + pad * 2 + 2;
// seperate output from input
cout << std::endl;
// invariants
int r = 0;
string::size_type c = 0;
while (r != rows) {
while(c != cols) {
if (r == 0 || r == rows -1 || c == 0 || c == cols -1) { // if in bordering column or row
cout << "*"; //output *
} else {
if (r == pad + 1 && c == pad + 1) { //if on row for greeting
cout << greeting; // write greeting
c += greeting.size(); // adjust invariant
} else {
cout << " ";
}
}
++c;
}
++r;
cout << std::endl;
}
return 0;
}

Answer 1

Consider moving the column counter c to nearer where you use it, then as tuckermi says it will start at 0 for each row.
while (r != rows) {
string::size_type c = 0;
while(c != cols) {

Answer 2

At the bottom of your outer loop you need to reset the variable c to zero, otherwise it keeps its old value and won't re-enter the inner loop.
A good way to accomplish this is to move the definition/initialization of the variable into the beginning of the outer loop. That way c will be reinitialized before you start the inner loop each time.

Answer 3

You're almost there.
You need to clear c each row, and you need to take one off the greetings.size() to make it format properly (accounting for the fact you will be incrementing it later in the loop)
// ask for a person's name, and greet the person
#include <iostream>
#include <string>
using std::cout;
using std::cin;
using std::string;
int main()
{
// fetch name
cout << "Please enter your first name: ";
string name;
cin >> name;
// message
const string greeting = "Hello, " + name + "!";
// padding
const int pad = 1;
//desired rows/columns
const int rows = pad * 2 + 3;
const string::size_type cols = greeting.size() + pad * 2 + 2;
// seperate output from input
cout << std::endl;
// invariants
int r = 0;
while (r != rows) {
string::size_type c = 0;
while(c != cols) {
if (r == 0 || r == rows -1 || c == 0 || c == cols -1) { // if in bordering column or row
cout << "*"; //output *
} else {
if (r == pad + 1 && c == pad + 1) { //if on row for greeting
cout << greeting; // write greeting
c += (greeting.size()-1); // adjust invariant
} else {
cout << " ";
}
}
++c;
}
++r;
cout << std::endl;
}
return 0;
}
http://ideone.com/mb9InW

Answer 4

Apart from reseting the variable c in the outer loop, you are not getting padding between the asterick and the message. So for that include the below code just after where you are printing the message.
for(int i = 0;i<pad;i++)
{
cout<<" ";
}