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'