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)
* **     *   ****  **   ** **
* ** **  * **    * *  ****    *  **   ***     * * ** ** * *  ** *  
 * * *  **    *  * * * * ** *   *  **  *** *    *  ** ** /= 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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}



int main(void)
{
**  * *  **** * **  * n;
****    ** ******** **  *** ** *  &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
* ***     *   **  **  *        * **   * ***** ******* **   *
**** *** * ** *   ** **    * *  * **** ***** *  ***       ***  * * *  **  **** *  *  *   **   * ****   ***    **    **** ***** * ********* **      *   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;
* ****   **  **** 
  * *** ****  ** *  *  *
 ** *  *    * * ***  * *  *  *   *  **  
}

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)
 *  ******   * *  ****  *** *
 *  * **    * * * *  ** * *   *   **          *    **      * *  *
* *  *  *** * ****** **  ***  *    **  * * *  * **    **  ++;
**   ****** *** **   ** *  * 
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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'