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'