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'