Question

How to remove digits from left to right from a number one by one until the number remain one digit in C

Answer 1

#include <stdio.h>
#include <math.h>
 
int truncate_left(int num) {
    int total = (int)log10(num); // total - 1 = 3
 
    // pow(10, total)); // = 1000
     
    while (num > pow(10, total)) {
        num -= pow(10, total);
    }
     
    return num;
}
  
int main(void) {
    int num = 74853;
          
    while (num > 9) {
        num = truncate_left(num);
        printf("%d\n", num);
    }
 
    return 0; 
}
  
  
  
  
/*
run:
      
4853
853
53
3
      
*/

 

70+ SQL courses for beginners and professionals

Answer 2

#include <stdio.h>
#include <math.h>
 
int truncate_left(int num) {
    int total = (int)log10(num); // total - 1 = 3
     
    int first_digit = num / pow(10, (total));
     
    return num - first_digit * pow(10, (total));
}
  
int main(void) {
    int num = 74853;
          
    while (num > 9) {
        num = truncate_left(num);
        printf("%d\n", num);
    }
 
    return 0; 
}
  
  
  
  
/*
run:
      
4853
853
53
3
      
*/

 

70+ SQL courses for beginners and professionals