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'