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'