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;
**   ****  * ** *    *   *   * *** **
**  *  * ** *   ** **  **
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******* * ** ***  ******* *  
** ** * *****  **    *** ****** 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'