Print Multiplication Table in Triangular Form using Haskell

This tutorial discusses writing a program to print the multiplication table in the triangular form in the Haskell programming language.

For example, the multiplication table for the number 10 in the triangular format is

1
2 4
3 6 9
4 8 12 16
5 10 15 20 25
6 12 18 24 30 36
7 14 21 28 35 42 49
8 16 24 32 40 48 56 64
9 18 27 36 45 54 63 72 81
10 20 30 40 50 60 70 80 90 100

Algorithm Steps

• Take input or initialize an integer variable n for which the multiplication table should be printed.

• Implement the program logic to print the multiplication table.

Example

Program to print multiplication table of a number in the triangular form.

-- function declaration for tablehelper function
tablehelper :: Int->Int -> IO()

-- function definition for tablehelper function
tablehelper n i = if(i==n)
   then printTable n 1
   else do
      printTable i 1
      tablehelper n (i+1)
      
-- function declaration for printTable function
printTable :: Int->Int->IO()

-- function definition for printTable function
printTable n i = if (n==i)
   then putStrLn((show (n*i)) ++ " ")
   else do
      putStr ((show (n*i)) ++ " ")
      printTable n (i+1)
      
main :: IO()
main = do
-- initializing variable for n
   let n = 10
-- invoking the function tablehelper
   print ("The multiplication table for number " ++ show n ++ " in the triangular form is:")
   tablehelper n 1

Output

"The multiplication table for number 10 in the triangular form is:"
1 
2 4 
3 6 9 
4 8 12 16 
5 10 15 20 25 
6 12 18 24 30 36 
7 14 21 28 35 42 49 
8 16 24 32 40 48 56 64 
9 18 27 36 45 54 63 72 81 
10 20 30 40 50 60 70 80 90 100 

In the above program,

We declared a function tableHelper as such it takes two integer arguments and returns an IO action. IO actions are the operations that use input and display consoles. The print function is an IO action as it displays output on the console.

In the function definition of the function tableHelper, two arguments are integer accepted n and a where n is the number for which the multiplication table is to be generated and a is a variable used for iteration. The value of the n is compared to i. If the value of n is equal to i, the control is transferred to the then block which is a base case where the printTable function is invoked with arguments n and 1.

If the value of n is not equal to i, the control is transferred to the else block, where the function printTable function is invoked with argument i and 1. Finally, the function calls itself recursively with arguments n and i+1. The function terminates when i+1 is equal to n.

We declared another function printTable as such it takes two integer arguments and returns an IO action. In its function definition, it accepts two integers n and i.

The function compares the value of n and i, if the n is equal to i the control is transferred to the else block which is a base case where the function prints the multiplicated value of n and i using the putStrLn function. If the n is not equal to i, the control is transferred to the else block where the prints the multiplicated value of n and i using the putStr function. And the function recursively calls itself with arguments n and (i+1) until the base case is reached.

These two recursive function works as a nested loop. In the main function, a variable is initialized for n. The function tableHelper is invoked with arguments n and 1 where n is the initial step of the iteration.

Note ? The function show takes the argument of a number and returns the parsed string of a number. "++" is an operator to concatenate strings in Haskell.

Conclusion

In this tutorial, we discussed implementing a program to print the multiplication table in the triangular form in the Haskell programming language.