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



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
**  ** *   *  * *   **   * * *    **   *  * *  ***     ***  * * **  
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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'