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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  *** **** ***       * * ** ** * != 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

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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**   ****  * *  ** *** * *       * * &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

Hidden content!
#include   ***** *   *  
#include   * *   ***    * 
int is_prime(int n)
{
* ****   *    *      ** *  divisor;
if (n<=1)
** ** *  *** *  *  false;
for (divisor *  *** ** * * ** *** **  *   
* * *      **** ****  
return true;
}
int main(void)
{
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* * **    * *  **  ***** *  * ** * * &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

Hidden content!
#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: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)
{
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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

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
***   **  **  **   *     ** * cnt=0;
 * *** *     * * ***  ** *  ***  ** != 0)
***  *        ***     *** 
*   * ** *   ***   * *** **   *   *  ****** * *  * ** /= 10;
*      ****** ****        *******  ** **    *******  ** *
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** *  *** ** * * ***   ** cnt;
**   *   **   * **  *  *       

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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*  *** *** ****    *  *       ** * 
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   **** * **  **   **   ****   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 9

Hidden content!
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

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'