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'