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'