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

內容已隱藏
#include <stdio.h>
int num_digits(int n)
{
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**   *  *     *   **   ***** * * * ** * != 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 2

內容已隱藏
#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

內容已隱藏
#include   *** *  * ** * 
#include  *** **    *** 
int num_digits(int n)
{
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*   * *  *   * * * 
*     * **    *  *** *** * 
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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

內容已隱藏
#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
*****  **    * **   ***  * ***   ***  **  **      *  **  *  * * *
 * * *  *      ***  ***   *  ** ** * ***** *  ******    *     ** ** *** ** *  ** **  **    ** **** ******** *  *   **** * ** ** ** *      ***** **      *       *** function return 0
   *  *  *  *   ** *** *  **        ***   **     ** *   **** *      *
   *  * *  *   *** ****** 0;
}

Comments

Case 0: Wrong output
Case 1: Wrong output
Case 2: Wrong output
Case 3: Wrong output

Answer 5

內容已隱藏
#include  ** *  *** **  ** 
int num_digits(int n)
{
 *  *** *   * ** ** ***
** **  **  *****   ******** * 1;
* **   ** ****** *  
** **  **  * ******  *  ***     
*      * * **  *  *  * * * *      *  * **
}

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

內容已隱藏
#include <stdio.h>
int num_digits(int n)
{
 **     *   * * * * *  ** *    count=0;
 * ** **   *   * ******  *      != 0)
  ****  *    * *   *           **
  * ******* ****** ***  *  ** ** *  *  ***  **** * *** 
   *  * * ** *******    * * ****          ***  ****      * * /= 10;
   **  *   **   ** *  
** *  *     ** **     ***  *****  **  count;
}

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 7

內容已隱藏
#include <stdio.h>
int num_digits(int n)
{
 ** ***  *   *** *****  **  *  cnt=0;
   * *** *  *  * **  ****** * ** != 0)
   * *  *** ******* **    *   
 *  *    **      * *  * *    *   * * ** *      * * ***** /= 10;
   *  *   *    *  **  ***  **     * *  * *  ***  ***   **** 
 * *  * *   ****  *  *
  *      **********   *  ****   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

內容已隱藏
#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

內容已隱藏
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

內容已隱藏
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'