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)
{
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}

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



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)
{
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 *     *   ** **       * ****** **  *  &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;
**  **** * **  **  ****
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   **** * **  **  **      ** 
}

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;
*        ** ***  *  *  ****
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}

int main(void)
{
*     * ** * **  *  **    **  n;
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**   * * ** **** ****  * *   ** *   *      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;
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* *****   * *** *   *  * 
 *  *    *    *  * ***   * 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)
      ** * **** ** **   **  *   
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 *   **  *   **     *  **    ****  *  * *    *  ** * ***** ++;
   ** * ****   *  *  **    
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 *   ** ** ** **   **  *   **  *** 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'