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;
 * *    ** ****** **   **     **      ** 
*** **** *    **** **  *** 
* ***** *  **   *****    *    *****   * *  *   *    **   **  *
 *   ** ***  ** *      *  ** 
  *** * * ****  ** * ***    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)
{
*      * *  * * *  *    *  
*  ****** **  ** ** *   **  * *** 1;
*** ** **  * * **  ***
 * ***** ** * **  **  **
    ****       * ** * * *** * **  * 
}



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
* ** *   * **   * *** ** *** * *** ******  **   *** ***    *  *** *  
*    **   *** ***  ** *    *   *  ** ** **  **   * * * ******* *  * * **    * *  *    * * * **** *      *  ** ***  * *** *  ***  **  * ** *  *  * *  ****   *     ***  * * *** 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;
 ****      *  ** **** *  *******  *  * **   &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'