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'