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'