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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** * * *   **    ** * *  * *          **  ****   *  *  ** * 
       * *   * * *****  
**** **        *  *** * * **** ** * i;
}

int main(void)
{
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     **      *  **  ***  * * * **    ***  **  &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;
  *  ***  ***  *    *
*  * * *    **     **  * 
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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'