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'