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'