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'