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'