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'