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'