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'