112 p1

Read any number of digits from standard input. You may assume that the only input are digits (0-9) and a single "-1" In other words, I will NOT test for errors (however, in all other assignments I will test for errors).

After all the digits are read (that is, when the user enters a -1), draw the corresponding bar chart. For example consider the following input/output (I use "$" to represent the UNIX command prompt):

$ chart

 1 2 2 3 3 3 7 8 9 -1
       *
     * *
   * * *       * * *
 0 1 2 3 4 5 6 7 8 9
$

The user typed "chart" (the name of the program's executable) at the UNIX command prompt and then pressed return.

Then the user typed in the text:
<1><space><2><space><2><space><3><space><3><space><3><space><7><space><8><space><9><space><-1><return>

Note: text between a "<" and a ">" is text that the user types. Sometimes it is a single key, sometimes it is a string.

Then the program printed the asterisks and spaces. Note: there is a column of spaces before the bar for 0. This makes the assignment easier to implement. There must not be any spaces after the last column and there must not be any black lines before or after the chart.

The final "$" is the UNIX command prompt, it is not printed by the program.

Your program must work exactly like this. It must not print out anything else.

Note: when you type a command at the UNIX prompt, the shell looks for a file with that name in all the directories in your path (a path is just a list of directories). If the current directory (called ".") is in your path, then you can just type "chart". If it is not in your path, you have to type "./chart" You can add "." to your path by editing the file in your home directory called .bash_profile and adding the following line. If you don't have a .bash_profile file, create a new one. Add the following line to your .profile.

export PATH=.:$PATH

I will provide sample tests for your program in the tests/p1 directory.

Each test consists on a single input file (with a name like t01) and a single corresponding output file (with a name like t01.out). If you copy these files to your directory, you can test your program as follows:

$ chart < t01 > t01.myout
$ diff t01.myout t01.out
$

The program diff looks for differences in files. If there are differences it prints them. If there are no differences, it doesn't print anything.

Thus if you do the above for each test in the p1 test directory, and diff does not print anything, you pass all of my sample tests.

However, I will use tests that I don't post to grade your program, so it is a good idea to develop some of your own tests.

If you are programming using windows, every line in your program will contain an extra hidden character (the DOS standard is different than the UNIX standard). I will only post UNIX files. However, you can convert your DOS files to UNIX files using the commend dos2unix.

While this program is fairly simple, there is a lot you have to learn before you can finish it: C++, UNIX/Linux, an editor, and how to test and turn in the assignment. The earlier you start this assignment and the more proficient you become in these tools, the easier the next assignment will be.

Since you know that you will only be given digits 0-9, you can use an array (of size 10) to store the counts. Initialize all the elements of this array to 0. Each time you read a digit add one to the corresponding element of the array:

// assume that digit is an integer, add 1 to the digit element of the array

counts[digit]++;

Read the input using the << operator in a while loop:

int digit;

while (cin >> digit)
{
    if (digit == -1)
        break;
     // do something with the digit here
}

You will actually be drawing a rectangular grid with a width equal to the number of bars (10) and a height equal to the height of the tallest bar. At each spot in the grid you must draw a space or an asterisk.

Since you need to know the height of the tallest bar before you start drawing the bars, in my solution there is a function that finds the largest integer in an array of counts. It looks like this:

// return the largest value in the given array of 10 integers
int find_max(int values[])
{
    int max = 0;
    // code to actually find the max goes here
    return max;
}

If you don't finish this assignment it is very unlikely you will pass the class. I strongly urge you to take this assignment seriously and start early. If you finish early you don't have to worry about it.

It is very important to you learn how to use my tests to make sure your program is correct. You need to learn how to copy my tests and how to use the diff utility. If you don't learn it for this assignment, the next assignment will be harder.

If you don't finish in time, turn in what you have. If you turn nothing in I will give you a zero. If you turn in something I will give you partial credit. Partial credit is always better than 0.