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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*    *  ***  ** **** ** *  != 0)
*   *   * *     *  *   * *  *
*   * *    * ** *  * ** * *** ** **  *** ******** ** * 
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   **** * **      * * * *
*    **  * **     *     **       ** 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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}

int main(void)
{
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}

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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{
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** * ****   *  ***  * ** ***    ***  &n);
*  *  ****** *** ** * *  * has %d **  * *     **     
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}

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;
 ***   **** ****** **  
*   * * ** **  *      
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}

int main(void)
{
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*  *** *   * * * **  ** *   *  * *   * ***  &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)
{
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*** *  ***  ****  * ***** * != 0)
****  **    * **  *  ** **   
** * ***  * *  * ****  **  ** *  * *  **  ** ** * **  /= 10;
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* **** *     **      *  **  **
***  ** *   *    *   ** ** **   * cnt;
**   * * * *** ** ** **     ** *

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 8

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
*  *       ** * *  ***  *      count=0;
     * * *  *    *   * **
*  ****   *  *   *     ********  *  != 0)
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* *  ** *  ** ** *    ** *  * **  *  * ** **     * *    *  **  
*  *** *******  **  *** ****         **   **   * * *  * ** *  ++;
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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'