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'