Displaying a character based on integer entered by user - c++

Question

I am sure this will seem very novice to many on here but I am currently trying to learn C++ and have an in depth full understanding to apply my knowledge in the real world.
The Problem Description:
Write a program that graphically depicts an integer’s magnitude by using asterisk, creating a
histogram. Hint: The inner loop handles the printing of the asterisk and the outer loop handles
exciting until zero is entered. Make sure you don’t accept negative numbers.
Sample run:
Enter a positive integer (0 to quit): 5
*****
Enter a positive integer (0 to quit): 8
********
Enter a positive integer (0 to quit): -5
Enter a positive integer (0 to quit): -10
Enter a positive integer (0 to quit): 15
***************
Enter a positive integer (0 to quit): 0
Good Bye!
My Current Code (I know this isn't right by any means, but helps demonstrate my thinking, I know you need to use a nested loop to answer this properly.):
#include <iostream>
using namespace std;
int main()
{
int ast; //Number of asterisk wanted to be displayed
char asts='*'; //Actual display coressponding to asterisk
cout<<"Enter a positive integar, (0 to quit)"<<endl;
cin>>ast;
while(ast!=0)
{
if(ast>0) // Ensuring no negative integars are entered
{
asts=ast;
cout<<asts<<endl;
cout<<endl;
}
else //Display if negative or other invalid data is entered
cout<<"Invalid Data, negative values are not accepted, try a positive integar or 0 to quit"<<endl;
cout<<"Do you want to continue? If so, enter another integar (0 to quit)"<<endl;
cin>>ast;
}
cout<<"Thank you for using the program."<<endl;
return(0);
}
Thank you for the help ahead of time!
-Colin

Answer 1

The basic idea is (with pseudo-code):
get number of asterisks
while number is not zero:
if number is negative:
output error message
else:
do number times:
output *
output newline
get number of asterisks
Your nested loops there are while number is not zero and do number times.
However, one of the earliest skills you should learn as a developer is to properly assign tasks to specific pieces of code (methods, functions, libraries and so on). In particular, it's a good idea to modularise your code so that each piece has a well defined purpose, then build the "upper" layers out of those pieces.
To that end, this is how I would approach the problem. First, define the functions that would be useful in this case.
Start with getAsterCount() which is responsible for asking the user how many asterisks they want and verifying that it's valid (asking again and again, until it is). For example:
#include <iostream>
int getAsterCount() {
// Until we get valid response.
for(;;) {
int count;
// Get value, checking for error, forcing exit if so.
std::cout << "Enter the number of asterisks, zero to exit: ";
if (! (std::cin >> count)) {
std::cout << "*** ERROR: could not read number\n";
return 0;
}
// Any non-negative value is allaowed.
if (count >= 0) {
return count;
}
std::cout << "That was less than zero, try again.\n";
}
}
Once that's in place, you never have to worry again about the user providing invalid information for this program, since this function will capture it (and you can call it from anywhere, as shown in the main() function below.
Next, provide a function that will actually output the asterisks, based on the count you now have:
void outputAster(int count) {
// Simple loop for asterisks then new line.
for (int i = 0; i < count; ++i) {
std::cout << '*';
}
std::cout << '\n';
}
With that in hand, your main code becomes the conceptually much simpler:
int main() {
int count = getAsterCount();
while (count > 0) {
outputAster(count);
count = getAsterCount();
}
std::cout << "Thank you for using the program. Now get off my lawn.\n";
}

Answer 2

Right now you are trying to do:
asts=ast;
Which doesn't make much sense, as this will only assign the entered integer to asts.
To print the magnitude in * you need to loop from 0 to the inputted integer and print out an asterix every time:
for(int i = 0; i < ast; i++) {
std::cout << "*";
}
std::cout << "\n";
Output:
Enter a positive integar, (0 to quit)
5
*****
Do you want to continue? If so, enter another integar (0 to quit)
3
***
Do you want to continue? If so, enter another integar (0 to quit)
5
*****
Do you want to continue? If so, enter another integar (0 to quit)
0

Answer 3

I like a somewhat different approach, without a loop.
char asts[] = “*********\n”;
After checking that the input value is in range, just write out the tail of the string:
std::cout << (asts + 9 - ast);