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'