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'