Practice Assignment

Information

1. Write a program that prints out the sum and product of the digits in an integer. Here are a few sample runs:

   Enter an integer (1 to 2,147,483,647 without commas): 1776
   The sum of the digits in 1776 is 21.
   The product of the digits in 1776 is 294.
   
   Enter an integer (1 to 2,147,483,647 without commas): 8
   The sum of the digits in 8 is 8.
   The product of the digits in 8 is 8.
   
   Enter an integer (1 to 2,147,483,647 without commas): 12345
   The sum of the digits in 12345 is 15.
   The product of the digits in 12345 is 120.
   
   Enter an integer (1 to 2,147,483,647 without commas): 2048
   The sum of the digits in 2048 is 14.
   The product of the digits in 2048 is 0.
   

   The numbers in RED are typed by the user.

   The name of the file should be sumdigits.c and the command to compile it will look like this:

   gcc -Werror -Wall -Wextra -ansi -pedantic sumdigits.c -o sumdigits -O2 -Wno-unused-result
   

   output-sumdigits.txt This output was generated by running the program 10 times, using each of these numbers:

   1
   42
   555
   1729
   65535
   142857
   8675309
   63288349
   999999937
   2147483647
   

Notes

• Approximate number of lines of code: 12
• You should use the previous practice (numdigits) as a starting point.
• You must use a loop (for, while, etc.) and can not use any conditionals (if, switch, etc.)

• Hint: You will need to use the modulo operator (%) to extract each digit.
• If you do something like:

  value % 10
  

  this will give you the right-most digit, which you can then use in your calculations.
• You don't have to worry about invalid input. You can assume that the user is going to input an integer within the specified range.
• You are only prompting the user once, printing the sum/product of the digits, and then ending.
• The first time you redirect to a file, use a single greater-than symbol (>):

  sumdigits > myoutput.txt
  

  On subsequent redirects, use two greater-than symbols with no space between them (>>).

  sumdigits >> myoutput.txt
  

  This will append to the existing file, rather than overwrite it. Of course, you won't see any prompt because that, too, is being redirected to the file.

For students that want to practice their C-fu

• Re-prompt the user on invalid input (using some kind of loop, preferably a do...while).
• Allow negative numbers.
• Allow floating point numbers. This will require a different technique and will be much easier to do if you convert the number to a string at first.