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)
{
**  * * * *** **** *  * * *** *  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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**  * ** * * ****    * *  ** ***   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)
{
*** **   * *   ** *   * ***
*    *  * *  **     ** * * *  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: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)
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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 7

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
 * * *** ** **** * * **   * ** cnt=0;
** *  *  *** **    **    ** * ** != 0)
 * * ** * ** * * **** * *    
  ***  ***  ***   *  *  *****    * **   **  *  **  * * /= 10;
  ** *  * ** ****  ***          **   ** ***    *       *** 
** * * **    *     *   *** *
*  ****   *   * ***** **  cnt;
****** * * ** * **** **  * *

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