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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**** *   *   *   ***   *  * *** 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  * *** **  ***** *       
*  * *** *  * *****  ******* 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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  * **  *** * *** *   **** 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 *  *  ** * * *   * * *    
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return true;
}
int main(void)
{
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***  ** * **   ***** * ****  * **** *  ** &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)
{
*****  *  ** * *    *  **** *
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* *  ********   *    
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}

int main(void)
{
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 * ** *   *** ** *    ***  *   has %d *** ****  * ** * ** *  *  
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}

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)
{
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  ** *       ** **   ** * * * **  != 0)
  *  *** *  * *  *       * *
 *   * * *** **  *    *  *****  * * * *   **  *  * * ***
*** * *** *  *  * **   **    * *  **      ** ****   *   /= 10;
**** * * *  * *  *  * ** **
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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 7

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

*     *  ***** ***    * **  * * * *    * *
* *** * *    ****   **********  OF YOUR CODE*/
*** *    *   ** *  **  num_digit;
}

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