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
 ***  * *   * ** *   *  *      * ** **        *  ** *   ***  ***
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 *  ** * * *** *  *   *       *  **  ** * * ****  * ****      *   *  * ** * 
 * *** *** ***  * * * * 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'