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'