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'