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'