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'