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'