Count The Number Of Digits In C

Approach

• ✅ Firstly, the number will be entered by the user. Suppose we declare the variable 'n' and stores the integer value in the 'n' variable.
• ✅ We will create a while loop that iterates until the value of 'n' is not equal to zero.
• ✅ Suppose the value of 'n' is 123.
• ✅ When the first iteration executes, the value of 'n' will be 123, and the value of count will be incremented to 1.
• ✅ When the second iteration executes, the value of 'n' will be 12, and the value of count will be incremented to 2.
• ✅ When the third iteration executes, the value of 'n' will be 1, and the value of count will be incremented to 3.
• ✅ After the completion of the third iteration, the value of 'n' becomes 0, and loop is terminated as it does not satisfy the condition (n!=0).

Let's develop a software that will execute the aforementioned strategy.

#include <stdio.h>
int main()
{
   int n;  // variable declaration
   int count=0;   // variable declaration
   printf("Enter a number");
   scanf("%d",&n);
   while(n!=0)
   {
       n=n/10;
       count++;
   }
   
   printf("\nThe number of digits in an integer is : %d",count);
    return 0;
}

Output

Enter a number
The number of digits in an integer is : [value]

Next, we will explore the method of determining the quantity of digits without the reliance on a loop structure.

We can determine the quantity of digits by utilizing the logarithmic function. The count of digits is obtained by employing the formula log10(num) + 1, where log10 is a built-in function in the math.h library.

Let's see a simple example.

#include <stdio.h>
#include<math.h>
int main()
{
    int num;  // variable declaration
    int count=0;  // variable declaration
    printf("Enter a number");
    scanf("%d",&num);
   count=(num==0)?1:log10(num)+1;
   printf("Number of digits in an integer is : %d",count);
   return 0;
}

Output

Enter a number
The number of digits in an integer is : [value]

We are going to develop a C program that utilizes functions to calculate the total count of digits.

#include <stdio.h>
int main()
{
    int num;  // variable declaration
    int count=0;  // variable declaration
    printf("Enter a number");
    scanf("%d",&num);
   count=func(num);
   printf("Number of digits is : %d", count);
   
    return 0;
}
int func(int n)
{
    int counter=0; // variable declaration
    while(n!=0)
    {
        n=n/10;
        counter++;
    }
    return counter;
}

Output

Enter a number
The number of digits in an integer is : [value]

Now, we will explore the process of recursively determining the count of digits.

#include <stdio.h>
int main()
{
    int num;  // variable declaration
    int count=0;  // variable declaration
    printf("Enter a number");
    scanf("%d",&num);
   count=func(num);
   printf("Number of digits is : %d", count);
   return 0;
}
int func(int n)
{
    static int counter=0; // variable declaration
  if(n>0)
  {
      counter=counter+1;
      return func(n/10);
  }
    else
    return counter;
}

In the provided code snippet, we are determining the count of digits in an integer. The func method is invoked for this purpose. Inside func, a static variable named counter is defined, ensuring it is initialized just once. The recursive call func(n/10) continues until the condition (n>0) is met. Upon reaching the false condition, the function returns the value stored in the counter.

Output