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