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)
{
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**   *  ** **  * * ***       i;
}

int main(void)
{
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*    *  ****    ***    **  * **  ** *  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)
{
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**  *     *  ******     **  * ******
}



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;
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 *  **   *        *** * **   * 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'