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'