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'