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)
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** * **** *  ***  *  **** ***  * ** ** * ** *  *     **
*** *****  * ***  * ** * *  * * ** * *   *   * *   **** /= 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)
{
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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)
{
***  ** ***  * * ** * 
* *** *** **   *********  * *  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'