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'