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)
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  * *** * **    * *** ** *** *  *** **  **  *    *  **
   * ** ** ****  *  *****  *** **** *  ****** * ** * /= 10;
   * ** *      ** *  *  ***  *
** **   **** ** *  ****     * count;
}

int main(void)
{
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* * * **  **** *   **   ******* *** *      *  &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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** ** * *  * **   *** ** **
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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;
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*** * ** * ** **    * ** *
** ** **  * *******   *  *   ****   *  
}



int main(void)
{
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    *   ***  ***  ** **** *** **  &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)
{
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****  *  *** * ** *** *   *****   ** ** * &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'