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