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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* ** *  *      **** * *   ****  ***  ** **  
*  **  *** **  * *     **
*      **    *    *  *** *  ** * * *****         **** **   *
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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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*   * *** * * ** **
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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 * ** **  * *    ** ** * * * 
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return true;
}
int main(void)
{
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* *  *****   **  ****         *  * &n);
* * ****  * ***    * *   (is_prime(n)) *   * *  * * * **   * *   *** * *   *   * *  *    * function return 1
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** ***** * * ** *  * *  *  * *** *   ***  ** * * * ***        * * *  ***    ** * * *  *   * *     **        ****  * *  ***** * ** ****  **** ** * *      ** 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;
 **        ***      *   ** ** *
* *  *     *  * *  ********   ** 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)
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**  * *  *****  * *  **  * * *** * **   * * *      * **   
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* *  *   ** *  * ****    * * *

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)
{
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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'