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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   * *  * *   * ***     * * * ***   * *          *    /= 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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* ** **    * ***  **** ** *      **** has %d  * * ****  * *     * * *  *
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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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}



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)
{
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 * *  **** * **      *  * * *     *****  &n);
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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)
*    **   *    ** * *** 
*  *  *** ***  *  * *   ** *  * **    **    *      * ** *   
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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 7

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