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)
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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)
{
* *  * ** **** ** * *** * *  *  i;
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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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* * *** * ** *   **** * ***      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
**    *   ******* * ****  **  *  **** **  * ***  * *  *  **   *
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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)
{
*  ***  ****   **** **** * *  * 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'