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'