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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  *  * * **      *  *    * **   * * ****   * **  **  * *  **  **
   *  ** *    *  **  *****  **  ** **   * ****  * ** /= 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)
{
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}

int main(void)
{
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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)
{
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***  *** *   *   * *** * * * * ***   **   &n);
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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)
{
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**     * * * ** **   * *  * 1;
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**** ** ***** *** ***   ** 
** * ** ** * ******* ***   **   *  * 
}

int main(void)
{
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        **     * ***        * *  * * * &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)
{
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*   ** * **      *** * * * != 0)
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  * *  ****  * *  **   *      ** * **    ***   **** 
***** *  *     **  *   * **    *  *   *     * *  * *** /= 10;
*  * *****   **   * *   ****   
*** * *** ******** ***** * *** * count;
}

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 7

內容已隱藏
#include <stdio.h>
int num_digits(int n)
{
 *   * ** **    * * **  cnt=0;
  ***** ***  *  * *****  *  * != 0)
 ***  * *   **     ** * *** **
* ****** **  * ***** * * *       **** * **   *   * ** /= 10;
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* **   *   ***     ***  * ** 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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*    ***** ** **** ***    ****  != 0)
***  ** *   ** * * **   **
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***** *  ***** *  **      **  *
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}
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 9

內容已隱藏
int num_digits(int n)
{
  *   **** **** * **  * ** num_digit=0;/*INSERT YOUR CODE HERE*/
**    ** ** ***     *** *   **
***   **  ** ***  
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*******   *** ** *   * ***    ***  *       *  * *** ***
*  *   * ***   ****  *

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