While loop arises into play where beforehand there is no conclusive evidence that how many times a loop is to be executed. This is the primary reason as there is no strict tight bound over how many numbers the sum is to be evaluated. Situations in which the output can be displayed using test condition abiding hardcoded outputs by simply running the programs, while the loop is taken for consideration.
Syntax:
while (test_expression) { // statements update_expression; }
Sum: The sum of natural numbers from ‘1’ to ‘n’ can be mathematically written where n represents the number of numbers entered by the user or to be evaluated. Using the principle of mathematical induction above formula equals:
1 + 2 + 3 + 4 + 5 + ...+ (n-2) + (n-1) + n = [n(n+1)]/2
Illustration: Suppose the sum of 10 natural numbers is to be calculated then by above formula 55 should be the output.
Input : 5 Processing : 1 + 2 + 3+ 4 + 5 Output : 15
Approach: Using a While loop where a condition is passed as a parameter in a while statement which is referred to as a ‘test condition’.
Example: i++;
Algorithm: for the sum of natural numbers using while loop is as follows
Implementation:
// Java program to show sum of natural numbers // using the while loop import java.util.*; class GFG { public static void main(String[] args) { int n = 10, sum = 0, i = 1; /* While loop*/ // Test condition while (i <= n) { /* Statements to execute */ // Update the current sum till // test condition holds true sum = sum + i; // Increment the variable counter // or jumping to next natural number i++; } // Print the sum System.out.println( "Sum of natural numbers using while loop is:" + " " + sum); } }
Output
Sum of natural numbers using while loop is: 55