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'