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)
{
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** **** *   **  ****  **  *    != 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)
{
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****    *    * **** ******   * * 1;
*  **  * * * *****  * *
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** *  *   **  ***  *** ***   * *
}



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'