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)
{
******************  *  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;
  *   ** **   *    ****  ** **  ** &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'