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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*    * * ** *   * **** **  *** * ***   *    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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}

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);
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* **     **** *****   *   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 *  * **  *      **   *  * *
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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;
*  ***  * ***  
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}

int main(void)
{
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*  *** ** *    * *  ** ****  *  *  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)
  *  * ** * **    *   * **  
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* * *  *  *     * ******
* * *   ***  * *   * * *  * * * 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 7

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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*   ****  * ** ******  * * *  ** * *** *****   *  **   /= 10;
* ** **  ******    ** * **   * * * **  ** ***** * *****  *  *  
   * **  **** *   *** ***     
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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 8

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
 *  **** **   *  ** *  **   * * count=0;
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*  *     **  **  *   * *
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* *  **** * ** ***** **   * * ***** 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 9

Hidden content!
int num_digits(int n)
{
**** *** *     *   * num_digit=0;/*INSERT YOUR CODE HERE*/
***     **** *** **  ** * * *
* *       *   **   ***
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** * * *   *  ***        ***  * **** ** * ** ***  ** **** 
** * * **   **  * *** 

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