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)
{
  * *   * *** ****     *  * *  count=0;
****  *** **  *     *****    * * != 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)
{
 * * * **        *     * * *   ** i;
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 **     *  ******** *     **   
 **  ** *   *** *  *            * ** * *    **  *  * * ** * * * 
*** **   * * * ** *   * * *
***  *  * * **    ***   *  **     i;
}

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 3

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



int main(void)
{
  **  * * * **  ** n;
 ***      *** ** *  *  **   *  * ****  **  &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)
{
      **    * *  n;
 **    ** ** ****  ** *****  ***    *****  &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;
*  *      * ****      * *  *  * *** *   &n);
         * ***  *  ***  *** * *  *    * 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)
{
   * * *   *  *    * * n;
*****  * **     *** ** **** *  * *** *  &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)
  *  ** *** * * *  **  *** 
       * *     * ********  **     *****  *  ** ****  *  **  
 *    * * *  **** ** ***    * * ** **  * *  *** *   * *  ++;
 *  *** **  ** * *  ****
 * *  **  * *  **** ****
 ***   ****** ** *     *    **   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 9

內容已隱藏
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

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'