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;
**** * * *** *     * *  ***** **  *** **    
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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)
{
***  *** *  **  * *** *     
****   **  * *    * * *** * 1;
* *  ***   *** ** * ** 
*  * *  *  ** **    ***     
** *   *  *  *****  * **    *   **   *
}



int main(void)
{
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 *** ** * *   ***  * *** *** **** *  &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'