In this article we will show you, how to write a Java Program to Count Number of Digits in a Number using For Loop, While Loop, Functions and Recursion
Java Program to Count Number of Digits in a Number using While Loop
This Java program allows the user to enter any positive integer and then it will divide the given number into individual digits and count those individual digits using Java While Loop.
JAVA CODE
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// Java Program to Count Number of Digits in a Number using While Loop package SimplerPrograms; import java.util.Scanner; public class NumberofDigitsUsingWhile { private static Scanner sc; public static void main(String[] args) { int Number, Count=0; sc = new Scanner(System.in); System.out.println("\n Please Enter any Number: "); Number = sc.nextInt(); while(Number > 0) { Number = Number / 10; Count = Count + 1; } System.out.format("\n Number of Digits in a Given Number = %d", Count); } } |
OUTPUT
ANALYSIS
Within the following statements, System.out.println statement will print the statement inside the double Quotes and next we are assigning the user entered value to integer variable (Number)
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System.out.println("\n Please Enter any Number: "); Number = sc.nextInt(); |
Next line, we used the While loop and the Condition inside the While loop will make sure that, the given number is greater than 0 (Means Positive integer)
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while(Number > 0) { Number = Number / 10; Count = Count + 1; } |
In this example, User Entered value: Number = 1465 and we initialized the Count = 0
First Iteration
Number = Number / 10
Number = 1465 / 10
Number = 146
Count = Count + 1
Count = 0 + 1
Count = 1
Second Iteration
Within the first Iteration the values of both Number and Count has been changed as: Number = 146 and Count = 1
Number = Number / 10
Number = 146 / 10
Number = 14
Count = Count + 1
Count = 1 + 1
Count = 2
Third Iteration
Within the Second Iteration the values of both Number and Count has been changed as: Number = 14 and Count = 2
Number = Number / 10
Number = 14 / 10
Number = 1
Count = Count + 1
Count = 2 + 1
Count = 3
Fourth Iteration
Within the third Iteration the values of both Number and Count has been changed as: Number = 1 and Count = 3
Number = Number / 10
Number = 1 / 10
Number = 0
Count = Count + 1
Count = 3 + 1
Count = 4
Here Number = 0 so, the condition present in the while loop will fail
Last System.out.format statement will print the number of digits present in the given number as output.
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System.out.format("\n Number of Digits in a Given Number = %d", Count); |
The output of given variable 1465 is 4
Java Program to Count Number of Digits in a Number using For Loop
This Java program allows the user to enter any positive integer and then it will divide the given number into individual digits and then count those individual digits using Java For Loop.
JAVA CODE
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// Java Program to Count Number of Digits in a Number using For Loop package SimplerPrograms; import java.util.Scanner; public class NumberofDigitsUsingFor { private static Scanner sc; public static void main(String[] args) { int Number, Count=0; sc = new Scanner(System.in); System.out.println("\n Please Enter any Number: "); Number = sc.nextInt(); for (Count = 0; Number > 0; Number = Number/10) { Count = Count + 1; } System.out.format("\n Number of Digits in a Given Number = %d", Count); } } |
We just replaced the While loop in the above example with the For loop.
OUTPUT
Java Program to Count Number of Digits in a Number Using Functions
In this Java program we are using the same steps that we followed in our second example but we separated the logic and placed in the separate method.
JAVA CODE
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// Java Program to Count Number of Digits in a Number using Functions package SimplerPrograms; import java.util.Scanner; public class NumberofDigitsUsingFunctions { private static Scanner sc; private static int Count = 0; public static void main(String[] args) { int Number; sc = new Scanner(System.in); System.out.println("\n Please Enter any Number: "); Number = sc.nextInt(); Count = NumberofDigits(Number); System.out.format("\n Number of Digits in a Given Number = %d", Count); } public static int NumberofDigits(int Number) { for (Count = 0; Number > 0; Number = Number/10) { Count = Count + 1; } return Count; } } |
OUTPUT
ANALYSIS
If you observe the following statement, we are calling the NumberOfDigits (Number) method and assigning the return value to integer variable Count.
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Count = NumberofDigits(Number); |
When the compiler reaches to NumberOfDigits (Number) line in main() program then the compiler will immediately jump to below function:
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public static int NumberofDigits(int Number) { |
We already explained LOGIC above example.
NOTE: If we create a function with Void then there is no need to return any value but, if we declared a function with any data type (int, float etc) then we have to return something out from the function.
Java Program to Count Number of Digits in a Number Using Recursion
This Java program allows the user to enter any positive integer and then it will divide the given number into individual digits and counting those individual digits using Java Recursion concept. In this example, we are dividing the code using the Object Oriented Programming. To do this, First we will create a class which holds a method to count number of digits in a number recursively.
JAVA CODE
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package SimplerPrograms; public class NumberofDigits { int Count = 0; public int DigitsCount(int Number) { if(Number > 0) { Count = Count + 1; DigitsCount(Number / 10); } return Count; } } |
Within the Main program, we will create an instance of the above specified class and call the methods
JAVA CODE
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package SimplerPrograms; import java.util.Scanner; public class NumberofDigitsUsingRecursion { private static Scanner sc; public static void main(String[] args) { int Number, Count=0; sc = new Scanner(System.in); System.out.println("\n Please Enter any Number: "); Number = sc.nextInt(); NumberofDigits nd = new NumberofDigits(); Count = nd.DigitsCount(Number); System.out.format("\n Number of Digits in a Given Number = %d", Count); } } |
OUTPUT
ANALYSIS
NumberOfDigits Class Analysis:
First we declared an integer function DigitsCount with one argument. Within the function, we used the If statement to check whether the given number is greater than Zero or Not and if it is True then statements inside the If block will be executed. It means:
- Count will be incremented by 1 using Count = Count + 1
- DigitsCount (Number / 10) statement will help to call the function Recursively with updated value. If you miss this statement then, after completing the first line it will terminate.
TIP: If you declare a method with void keyword then we can’t return any value. If you want to return any value then replace void with data type and add return keyword.
Main Class Analysis:
First we created an instance / created an Object of the NumberOfDigits Class
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NumberofDigits nd = new NumberofDigits(); |
Next, we are calling the DigitsCount method.
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Count = nd.DigitsCount(Number); |
Lastly, System.out.println statement will print the output (987654321 = 9).
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