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'