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;
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*  *    * *  * * *** ***   
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*****   *  * *  ** * *  
***  *  ** ***** **** *  *** **  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)
{
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    ** * ******  *  *   **  1;
**** ***   *** * ***  
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  **  ***   **  * *** *      *   ***
}



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'