How does a C program to count number of digits in an integer work?

 Courtesy: Programiz.com


The integer entered by the user is stored in variable n. Then the do...while loop is iterated until the test expression n! = 0 is evaluated to 0 (false).

  • After the first iteration, the value of n will be 345 and the count is incremented to 1.
  • After the second iteration, the value of n will be 34 and the count is incremented to 2.
  • After the third iteration, the value of n will be 3 and the count is incremented to 3.
  • After the fourth iteration, the value of n will be 0 and the count is incremented to 4.
  • Then the test expression of the loop is evaluated to false and the loop terminates.

Note: We have used a do...while loop to ensure that we get the correct digit count when the user enters 0.

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