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'