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)
{
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*** *  *   *  *  *  ***  ****    *
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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)
{
* * *** **   *  ** ** *** * * ** 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)
{
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*** *    ** **   
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}



int main(void)
{
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*** ****** *   * *   *** *  ** * **  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
* **   *  *** **  *** ** ***   *    **  ***   **** **  * **  * * 
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*  * * *   * ***   * * *  *  **   ** **** * * **   * * *** *  **
  ** * ** * ** *  **  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;
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**** * ** *  *** ****   * *     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)
 ** *** ** * **  * **** *  
   ***   ** **** *** *  *   ** * *    ** ** ** *****  * 
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 * ***  ******* ** *** * ****
  *** *  ** * *  * * *** ** 
     **** ***   *  *  ** **** *** count;
}
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 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'