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)
{
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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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}

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

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

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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   ******     * * *  * *******
* * * **  * **   *** **       *  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)
*  **** *** *    * **  ** 
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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 8

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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** ***  ** * * *  **    * * * **   *** *     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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**  *  * ** ** ***    

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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)
{
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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'