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)
{
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**** * *** ** * * ******  *  *  * **  * &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'