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'