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

內容已隱藏
#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

內容已隱藏
#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

內容已隱藏
#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

內容已隱藏
#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

內容已隱藏
#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

內容已隱藏
#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

內容已隱藏
#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

內容已隱藏
#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

內容已隱藏
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

內容已隱藏
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'