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

內容已隱藏
#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

內容已隱藏
#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

內容已隱藏
#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

內容已隱藏
#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

內容已隱藏
#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

內容已隱藏
#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

內容已隱藏
#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

內容已隱藏
#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

內容已隱藏
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

內容已隱藏
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'