12-07 Exercise 2: Function num_digits

Question

Write a function num_digits(n) that returns the number of digits in n ( a positive integer). Hint: to determine the number of digits in a number n, divide it by 10 repeatedly. when n reaches 0, the number of divisions indicates how many digits n originally had.

寫一個num_digits(n)函數 計算n有幾位數

#include <stdio.h>
int num_digits(int n)
{
   /*INSERT YOUR CODE HERE*/

   /*在這裡寫你的程式*/
   /*END OF YOUR CODE*/
}

int main(void)
{
   int n;
   scanf("%d", &n);
   printf("%d has %d digit(s)",n,num_digits(n));
   return 0;
}

Please complete this program by only insert your code between those tags:

   /*INSERT YOUR CODE HERE*/ 
   /*END OF YOUR CODE*/

Example input

12347

Example output

12347 has 5 digit(s)

Remember: You may correct the cases, but your code always be revised!

Answer 1

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
   ****   *   *   **** *** ***  ** count=0;
* ***  * ***  *****  ****     *   != 0)
 * * *   **** **   ** ** *
* *  *** *****  ** **  ***  *  ** **   *** *** *   **  ***  *
      **     *    *   *******   * * ****     *   /= 10;
 * * *  *      **    *****
  *    **    *   * ****** *    *    count;
}

int main(void)
{
* * * ** ***  ***** * * **   n;
   * *   ***** ** * ** ****  *    * ** * * * ***  &n);
  **  * *  ****    *  ** ** *** **    * *    * has %d **   **   * ***  ** *** 
* *      *   **** * * * ** *   0;
}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 2

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
*** *** * ** * ********* *** * i;
* * ** ** *     **** ** ** * *   *    
  *****   ** *** ******
  ** *   **** *  ****   *  **      * *   ** **  *** *** * *   ***
 *  *    *     *** *** ** *  * 
 * * *    ***   * *** *   *  * *    i;
}

int main(void)
{
       *  * * **   n;
* ***   ** *   * *  ** * *****  *** &n);
 ***  **    *  * *     * *     *  * has %d  ***** *   *     ***   ** * 
* * **      *** ** ******* 0;
}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 3

Hidden content!
#include  **     * ***  
#include    *  **  * 
int num_digits(int n)
{
* ******* **** * * * ***  *
*   ** ** *  ****   * ***   * 1;
 ***  *   **       *
**  ***   ** **   **  ** 
*      ** *  ****** *  * * *   *  ** *
}



int main(void)
{
   *   **     ** n;
*   ****  ******    ** * **  *****  &n);
 * *  *   *    *  *** *** * ** *  * has %d ****      *     * *****
*   *****   * *   *****     0;
}

Comments

prog.c: In function 'num_digits':
prog.c:8:6: warning: implicit declaration of function 'abs' [-Wimplicit-function-declaration]
    n=abs(n);
      ^~~

Answer 4

Hidden content!
#include *** *  ******* 
#include *  ** * *  **   **
int is_prime(int n)
{
  *  *** *   **   ** divisor;
if (n<=1)
** **   ** ** * * * false;
for (divisor ** *  *  ******  *  ***  
*  * * * * *    *  ****
return true;
}
int main(void)
{
* *  * *****   *   * **** n;
   * * **       *  *    *** *     *   *   * &n);
*** *** **      * *      (is_prime(n)) * ** * *** *   ******* *  ** ** * **    ** * * **     *  function return 1
* *** * *** ** * ***    * *  ** *    **** * * *  *   ** *   * 
*    *** * *     **  **  *   *** *     ** * * **       *  * *    ** * * ***** ** *  *  *   *   *   * *   ** * *** ***** *  * ** *   * ** * * *   *   *    *  *    *  *   function return 0
***** ** * * ***     ***   * * ***  * * ******       *  *   *   * * *
* ***  ***  *****  ***  * 0;
}

Comments

Case 0: Wrong output
Case 1: Wrong output
Case 2: Wrong output
Case 3: Wrong output

Answer 5

Hidden content!
#include  ***  ***  *** *
int num_digits(int n)
{
* * * *  * *    ** ***
**  *   *  **  *     ***   *  1;
   *** *     **   *
    ** **  * * *  * ****  * ** 
  *** **  *  **       *****  
}

int main(void)
{
     ***  ** *  * * *     ** n;
 * *** ****   * **  *  **** *     ******  * &n);
** *****  *  * **  *    ** ***  *    has %d *   **** **    *  
* ** * *   *   *****    ** 0;
}

Comments

prog.c: In function 'num_digits':
prog.c:7:6: warning: implicit declaration of function 'abs' [-Wimplicit-function-declaration]
    n=abs(n);
      ^~~
prog.c:8:16: warning: implicit declaration of function 'log10' [-Wimplicit-function-declaration]
    return (int)log10(n)+1;
                ^~~~~
prog.c:8:16: warning: incompatible implicit declaration of built-in function 'log10'
prog.c:8:16: note: include '<math.h>' or provide a declaration of 'log10'

Answer 6

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
* ***    *         ***** ** count=0;
   **        * * **   * *   *     != 0)
 * *  **** ****  ****
* ** **  **** ***   ** ** *     *** *  **   ** * **** **   *
 ** **** **  **  ****    ** ** * * ******* **  /= 10;
 * *** ** *** * ***   *** * **
 * * **  *  *  ** *  *** ** * * **   count;
}

int main(void)
{
** ** ***** *** * *   *      n;
** * * *** *  ****     **** **   ** *   * ** *** &n);
*  ** *** * * * *          *    * has %d ** ***   *  ** *** ****** 
 *** **   **** * * ***      0;
}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 7

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
 ***  *** **  ** *    *     *  cnt=0;
*  *   ******  ** **** *    != 0)
  * **** *     ****   * *  * ***
  *    *** ****    **** *  *  *  ***** * * *  *   *   *  *    * /= 10;
*   **  * * * ** **  *     ** *******  *  ***  **  ** * *   
*    *     ****** ****  
  * ** * *  **      *   *   * *  * * cnt;
*   ***      * * * ** **  ** 

int main(void)
{
 *    ***    ** *   ** *     * n;
* ***** * ***   ** *   **     *    * * *      ** &n);
    *  *  * **   * * ** *****  * *  * * * has %d **  *  **     *   * *
*** **** *    * * ** * * ** * * * 0;
}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 8

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
  ****** *******   *  *      count=0;
***   *   * ** **    ***  *  
****    ***  *  *   **        *** != 0)
*   *  * *  *** **   *
 ** * *  * **    *   *    * *  **   *  ** ***** *       
 * *** * *  *     *    ***** * * **  * *   ** ** ** **** ++;
** *** ****** ****  * *   ** 
 * ***  *  **      ***     
*** * *******  ** ** ** ** count;
}
int main(void)
{
*     **  **** **  * *    * n;
 **  ** *    ***          *** * * * ** *** *    &n);
    *  * *     **  ****** * * ** * ***  has %d  *         ** *   * **** ** 
** * * *  *  *  *    ****  ** ***  0;
}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 9

Hidden content!
int num_digits(int n)
{
*     * * *** **  * *     num_digit=0;/*INSERT YOUR CODE HERE*/
 ********  ***  *      * 
*  * ***  **  *  * **
  * ***   *  *  * * ****    ** *  *  *  *  *   ***** 
  ***  * *  ****  *  *  * *  ** *     ** **  ** ** ****  *
   **  *      *   * *

      * *    ** *    * ***   ***     *
* ***** * *   * *  * * OF YOUR CODE*/
     *     *** * * ***  * num_digit;
}

int main(void)
{
*  *   *    * ** ** ** n;
  * **  *** *** *      *  *** **** ** &n);
 ** *   *** ** *****   ***   **  has %d **  ** *    **** ***  *  
* * * *  ** **  *    0;
}

Comments

prog.c: In function 'main':
prog.c:18:4: warning: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
    scanf("%d", &n);
    ^~~~~
prog.c:18:4: warning: incompatible implicit declaration of built-in function 'scanf'
prog.c:18:4: note: include '<stdio.h>' or provide a declaration of 'scanf'
prog.c:19:4: warning: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
    printf("%d has %d digit(s)",n,num_digits(n));
    ^~~~~~
prog.c:19:4: warning: incompatible implicit declaration of built-in function 'printf'
prog.c:19:4: note: include '<stdio.h>' or provide a declaration of 'printf'

Answer 10

Hidden content!
int num_digits(int n)
{
 *   ***  * *  **    count=0;/*INSERT YOUR CODE HERE*/
** * ** ***** * *** **  * ***
*   *  * *  *  * * * 
* *      * *    ** ****   *   *   ** * ** *  **  *  *
 ******* **   *  *** * ** *   ** **       ****  
   **** **  * **  *   

*** *    * *     ******* **  ** * **  ** *
   ****   ***** *     ** OF YOUR CODE*/
 ***   *  ** *  ** *   ***  * count;
}

int main(void)
{
  *  *****  ***  **   n;
 **  ** ****    * ****   * **** ** *  * *    &n);
** *  ** * *  *** *  ** ** *** ***  has %d ****** **        ** * **
   *  *  * *** ******   0;
}

Comments

prog.c: In function 'main':
prog.c:18:4: warning: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
    scanf("%d", &n);
    ^~~~~
prog.c:18:4: warning: incompatible implicit declaration of built-in function 'scanf'
prog.c:18:4: note: include '<stdio.h>' or provide a declaration of 'scanf'
prog.c:19:4: warning: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
    printf("%d has %d digit(s)",n,num_digits(n));
    ^~~~~~
prog.c:19:4: warning: incompatible implicit declaration of built-in function 'printf'
prog.c:19:4: note: include '<stdio.h>' or provide a declaration of 'printf'