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'