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'