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;
**  * **  ****  **  *** *      ***  **  * ***
  * * **** *** *** ***   **  *
* *    *   * *  ***  ****** **      * *    *** **  *   ** 
     * * ** *       ** *  *
* * ****  * *    *  ** ****    * 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'