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'