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'