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)
{
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** ** **  * ***  * ** **** *   * * **  ***** **  &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)
{
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  * ***    * **    *  **  **    * i;
}

int main(void)
{
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** * *   * **   ****     ** **  **   ** has %d  ** * ****** * ** ****  *
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}

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)
{
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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
*   * *** ****** **     ***   *  *  * *    *  * * *  * ***   ****  
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* * ******  * *** ****  *  * *   * ****  * ** * * ** *** * ** ***  *
****    ** * ** **  * *** 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;
 *    * * * *  *****
***  * ** *    *    
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}

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