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)
{
** *  **    *      ***  *   i;
*       **  ***  **** **  *  * ****  ** *  *     *
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*  *    **   * **   *** ** **   i;
}

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 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;
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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)
  **** *************  *    * 
* * *  * * * * **   ** **  * *** * * *  * * * **  *****
* *   **   **** *** *** *** ****  **  ** ** *   ** * ******      /= 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'