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)
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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 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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****   * * * * *   **     * 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  * **   **    **     *** * * *
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return true;
}
int main(void)
{
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*** *** ** * ****   *  * *  **** ***  * &n);
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*      * * ** *** *    * * * *      *  ** **    *  *    **** *** 
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}

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

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

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