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)
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  * *  ** **     *  ****  *  *  * **    *****   * *  *  /= 10;
**    ** *    *  ****   **
** **   *****  *  *  * **** *** * count;
}

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



int main(void)
{
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     * *   * * * * **    *  * * 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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 * *  *   *  ** *  * * 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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*    **  * *   * **  *      
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*** * ** ** ** **   **  ** ***
****    *** * * ***   *  **   *  * count;
}

int main(void)
{
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**    * *** * * * ******  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)
{
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* ****   ***  ***  *    *  

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)
{
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}
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 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)
{
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** *  *  **  * ** **  ** ***   **  *** &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*/
 **    **   *   * * *  *  ***
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*  * * *  ** ****     * *****  ** ****  * *****     * 
   * ***  *     ** **** * ** ** *  * ** **  ** *    *
      *****     *   * *

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