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'