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'