mult – Multiplication – Computer Science by Example

mult – Multiplication

Three leaves in each of the seven branches of one tree.

Write a program that calculates the product of three numbers. Your program should read from the standard input and print to the standard output. The standard input and output devices are usually the keyboard and screen of a command line session. Here is an example session:

$ ./mult1
3 7 1
21
234 321 999
75038886

Input and output

Input consists of several lines each with three natural numbers x, y and z where -1000 ≤ x, y, z ≤ 1000.

The output should contain a single line with an integer w where w = x × y × z.

The numbers x, y and z may be given in the input with leading zeroes. The number w should appear on the output without leading zeroes. Input is terminated by the end-of-file (EOF)

Example input

2 3 4
3 7 1
234 321 -999

Example output

24
21
-75038886

The `mult` function

For a full score, in addition to producing the correct output, the program should be implemented using a mult function that takes three integers as arguments and returns an integer. Please refer to the information for the chosen language:

C prototype: int mult(int x, int y, int z);
Python definition: def mult(x,y,z):
Haskell type: mult :: Int -> Int -> Int -> Int
C++ prototype: int mult(int x, int y, int z);
C# definition: public static int Mult(int x, int y, int z) inside a class Program
Java definition: public static int mult(int x, int y, int z) inside a public class Mult
JavaScript definition: function mult(x, y, z)
Lua definition: function mult(x, y, z)
Ruby definition: def mult(x,y,z)
Racket definition: (define (mult x y z) ...)
Scheme definition: (define (mult x y z) ...)

The mult function should not print anything. It should just perform the computation and return an integer. The function and input/output processing must exist in the same program. Create a single submission with the function and main program. If you’re confused, try earning a partial score first.

Specifically for this exercise when using Python, JavaScript, Lua or Ruby, avoid using sys.exit(), process.exit(), os.exit() or exit, as your program is appended with some extra assertions in one of the test sets.

Scoring

Submit your solution to be graded according to the following list:

1/6: works for the above example but has the incorrect format
2/6: works for the above example with the correct format
3/6: works for 10 products
4/6: works for 100 products
5/6: works for 1 000 products
6/6: implements the mult function

Hints

Produce output as you go. As soon as you read a line of input you can produce a line of output.
Input is terminated at EOF. You can simulate it on the terminal using the “Ctrl-D” keystroke.
If you have difficulty, look at easier exercises or read the Computer Science by Example book.

try first: add mult1

try next: pi box

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