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'