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;
 ***  * ***  * *  *    *  *     ** != 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

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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* ** ********   ** ** **    
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*******     **  * *   *  *** 
      ***   *   *** * *   ***  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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 *      * ** ** *     **  *   * 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

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'