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

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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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 2

Hidden content!
#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

Hidden content!
#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

Hidden content!
#include    *** **  *
#include      **  *        
int is_prime(int n)
{
 **  *       ** *  **   divisor;
if (n<=1)
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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

Hidden content!
#include   ***** * *  * * 
int num_digits(int n)
{
** *  * ** *  **   * * *
***   **         *   ** ****    1;
*** * ***   *** * *    **
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}

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

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
*** * * ** * * **   * ***** count=0;
**     *   **   * * ***   **** *** != 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

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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**  ** ******* ****   *** ** **  != 0)
***  ** * ****   *   **    
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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 8

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
*   *****  *  ****   **  * * **  count=0;
* * *  ***   *   *    *** 
* *** ** ***** ***  ** *** ** * *  != 0)
* **** ***  *      **** 
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*** *  *   **** ***   ** ** *   
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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 9

Hidden content!
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

Hidden content!
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'