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;
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 ** *   ***** **** ***  *** 
 * ***     *** * *   ***  * *   ***  *  ******* *****   *
 * *  *  * *  * *** *  *** * **    * ** * * * ** /= 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)
{
****   ***  ***    ** **  
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***  * * * ** *** *      *
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* * *** *  * * *    * ** *** ** 
}



int main(void)
{
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 *   * *** **  ********  * *    ** *  &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
  ** *     *  **  *** *    * *      *  ***** *        *  ** * *
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**    * *   *          ***  **** ***  ***  *** **  ********    **    *  *** *
***   * * * *   ****    **  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'