Multiplication table program in C using For loop

Before we move on the program of multiplication table of any natural number, first we have to know about the For loop statement.

The syntax of ‘for’ loop in C programming language is given below:

for (initialization statement; test expression; update statement)
{
    /* main body of the ‘for’ loop */
}

How does the ‘for’ loop work?

In for loop, the initialization command is implemented only once.

After that, it checks the test expression of the loop and finds whether the test expression is false or true. And, for loop is dismissed if the test expression is false.   
If the test expression of the 'F' loop becomes true, then the program line provided in the F loop’s body is executed, and the update expression is changed accordingly.
Again, the entire process of evaluation is to be done. The loop executes its body until and unless the value of the test expression in for loop becomes false. The loop automatically terminates as soon as the test expression result becomes false.

The following program shows the multiplication table of any number entered by the user with the help of For loop in ‘C’ programming language:

#include <stdio.h>
int main ()
{
   int a, b; // declaring various variables without initializing their values
   printf ("Enter the natural number whose table you want to see here: \n");
// taking the value for output by the user as an input
   scanf ("%d", &b); /* assigning the value inputted by the user to the variable ‘b’ */
   for (a=1; a<=10; a++) // for (initialization statement; test expression; increment or decrement statement (for further evaluation))
{
      printf ("%d * %d = %d\n", b, a, (b*a)); // printing the result as an output value
   }
   return 0;
}

Output:

Enter the natural number whose table you want to see here:
10
10 * 1 = 10
10 * 2 = 20
10 * 3 = 30
10 * 4 = 40
10 * 5 = 50
10 * 6 = 60
10 * 7 = 70
10 * 8 = 80
10 * 9 = 90
10 * 10 = 100

Explanation of entire above program:

First step is to declare the variables a and b.
One more thing to notice in above-mentioned example is that both the variables are not initialized at the time of declaration. So, we let the user to input any natural number whose multiplication table is desired to be printed. The value entered by the user as an input is assigned to the variable ‘b’.

After that the ‘for’ loop is initialized. As we all know that FOR loop generally have three basic elements initialization statement, test expression or termination condition, and increment or decrement statement that changes the value after the execution of each iteration of ‘for’ loop.

Here, we initialized the value of variable ‘a’ equal to 1 and the termination condition is set that the value of variable ‘a’ must be less than or equal to 10. The modifying statement defined as a++ (an increment statement) that means the value of variable ‘a’ will be incremented after each and every execution of the ‘for’ loop.

After this, there is a print command to print the result as an output on the user’s screen.

The value of variable ‘b’ is 10 and it will not change throughout the entire evaluation of the ‘for’ loop as no increment or decrement statement is defined for variable ‘b’.

In the body of loop, we provided an operation b * a in the printf statement which multiplies the value of both variable and print the final value at last.

In the above program we have taken the multiplication table of 10.

So, value of b = 10 and value of a = 1.

And, the printf statement has printed the value 10

Then the increment statement incremented the value of variable ‘a’ from 1 to 2.

Hence, this time the printf statement will print the 10 * 2 = 20 on the screen.

And this process will execute for around 10 times and you will get the desired output same as the output of above program.

And as the value of ‘a’ will become 11 it will terminate the loop because the termination condition was set as a<=10 therefore it will find this condition to be false and dismiss the ‘for’ loop.