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'