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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 * *  **** * ***
*  *  ** *  * *** ****  ** **
** *  *** ** * * ** ** *** *    *  ** **
}



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)
{
 *    ** * ***  *   * *  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'