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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*** * *****     ***  * ** **    *   *    **** *** *  * **  * 
 *   **  * *** * *   *   *** * ****    *  **  **    /= 10;
**  *  *   **  * **   ** 
 **** *  **  * * ** ** ** **  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 2

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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}

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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}



int main(void)
{
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** * ** **   *  * *   ** *   * * *  * *** &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
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* ** * ** *** *  **  ***    **           *    **   *****  *** *  * *  *  *  *  *  ** **   ** * *******  ****   *  *** * *** *        ***   ** * ****      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)
{
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*****    * **** *  *** *** 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)
** * **** * ** ***  * *****  *
 **      ****** ****   ***   * **  *    *  ******  *   **     
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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 7

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