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)
{
 *   ** *  * * *** ****   *  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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   **      * **** ** * *  * * * **** 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
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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)
{
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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)
{
** ** ****  **  * *   ** cnt=0;
  ***  ***  *** ** *  ****  **  * != 0)
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* *****     ***   * ** *  * *  *   ** * *  *  *  ****** ** /= 10;
* *       *  ** *   **   * *    *   ** ** * ***  * *   *  ** * 
** **  ****   *  *      **  *
*   *** *** * *    ** ** **  *** cnt;
***   ***        **   * 

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 8

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 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'