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'