C Program to Find First Digit Of a Number

C program to find first digit of a number; Through this tutorial, we will learn how to find first digit of a number in c program using log() & pow() , while loop and functions.

C Program to Find First Digit Of a Number

• C Program to Find First Digit Of a Number using Log10() and pow()
• C Program to Find First Digit Of a Number using While Loop
• C Program to Find First Digit Of a Number using Function

C Program to Find First Digit Of a Number using Log10() and pow()

/* C Program to Find First Digit Of a Number */

#include <stdio.h>
#include <math.h>

int main()
{
  	int Number, FirstDigit, Count;

  	printf("\n Please Enter any Number that you wish  : ");
  	scanf("%d", & Number);

  	Count = log10(Number);

  	FirstDigit = Number / pow(10, Count);

	printf(" \n The First Digit of a Given Number %d =  %d", Number, FirstDigit);

  	return 0;
}

The output of the above c program; as follows:

Please Enter any Number that you wish  : 123
The First Digit of a Given Number 123 =  1

C Program to Find First Digit Of a Number using While Loop

/* C Program to Find First Digit Of a Number */

#include <stdio.h>

int main()
{
  	int Number, FirstDigit;

  	printf("\n Please Enter any Number that you wish  : ");
  	scanf("%d", & Number);

  	FirstDigit = Number;

  	while(FirstDigit >= 10)
  	{
  		FirstDigit = FirstDigit / 10;
	}

	printf(" \n The First Digit of a Given Number %d =  %d", Number, FirstDigit);

  	return 0;
}

The output of the above c program; as follows:

Please Enter any Number that you wish  : 2365
The First Digit of a Given Number 2365 =  2

C Program to Find First Digit Of a Number using Function

#include <stdio.h>
#include <math.h>

int First_Digit(int num);

int main()
{
  	int Number, FirstDigit;

  	printf("\n Please Enter any Number that you wish  : ");
  	scanf("%d", & Number);

  	FirstDigit = First_Digit(Number);

	printf(" \n The First Digit of a Given Number %d =  %d", Number, FirstDigit);

  	return 0;
}

int First_Digit(int num)
{
	while(num >= 10)
	{
		num = num / 10;
	}
	return num;
}

The output of the above c program; as follows:

Please Enter any Number that you wish  : 7895
The First Digit of a Given Number 7895 =  7

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