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'