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'