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)
{
* *  *    * *   ** * * ** * ***   i;
 *** *  ****  * **    ** * ** **  **    *** 
** ** * * *** *** * **  **** 
*  *** * ***  ****   *** ******   ** *    * *  *   *     ***  *  
*** * **   ***  **** ** ***
 * **  ** **  *    *** ********* 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'