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'