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'