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

Hidden content!
#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

Hidden content!
#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

Hidden content!
#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

Hidden content!
#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

Hidden content!
#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

Hidden content!
#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

Hidden content!
#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

Hidden content!
#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

Hidden content!
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

Hidden content!
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'