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'