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)
{
**** ** *  **  *** **  i;
*   ****  * * ** * *** *** **   ** *  **
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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)
{
* *   *** * *** *** * ** **
 * **     ***** ** *  *  *  * *    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
 ** * * *    *    ** ***  **   ***** ** ** ** *   **  *** ***  *** *
  * ** * *   *   ** ***** *   **  **    *** ** ***    * *  ** *  **  ***  ****   * ******** ****** ****   ***  **  *** **   ** * **  *  * ***  * *    * *** function return 0
***   * *****   * ** ** *   *   ***** ** *   * * *******    ** ** * 
  * *  ** **    *  **** 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'