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



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
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* *     *** *  *  * * ***  *** *  ***    ***    *  *******       *****   * ** ****  * *  ***  * * *******  **  *    *         *   * *   *** ****   ******** *  * *   * 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'