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!

Show more...

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'