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)
{
 **     *   *   * *  ** *  ** count=0;
 *****   ** * * **  * *   **** *** * != 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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***    *  **  **   ****  i;
}

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 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)
***  *  *   **   * false;
for (divisor     ** **  * *  * ***  ****
*******   * ****  *  * *** 
return true;
}
int main(void)
{
*  * *   * *** ****  *  *  n;
* *   *  * **  ***  ****** *   ***** &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)
{
*   *** *     *    * * * **** 
* ****     **  *  * *  ***** ***   * * 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)
* ***** *** ***     ** *   
** **   *   *   *      ** **    ** ***    ** **  * ** *  ****
****  * *** *  ** ***    *** ***   * ** * *    **** ****  /= 10;
** * *******  *******  **** * 
** *            ** **  ** **  **** count;
}

int main(void)
{
 ***  *  **  ***      ** *** n;
 ** * * **** *****  ** * ** *   ***  **     &n);
*  **** ******   * *** *  **** * *** ***   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;
  ** ** ***** *   ***  *** * * *   *  *   *   **      *  * * *
*       ***   * ** *  *    
 ** ** *** ***  *  *  **  ** * *  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)
   *   * ** *     * ** * *
* ***     * * **   * ***** **  ***** *   ** * ** *** **
* *   *    * ** *** ****  ***  *****          * **   ** ****  * ++;
 ** **  *  ***   *   * *  * ****
*** * * **   *  ** **  *   
** *  ** *** **   ****    ***    * count;
}
int main(void)
{
***  * *  *   * ** * ***** n;
* ***** ****     ****  ***      *  **** ** * *    &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*/
  **** ****   *** * *  * ***
 * * **  * *** **  *
  ** ***** *     *** *  **** * *****    * ** ***  *   ****
  *  * ****  **  **    ** *   *** * **  * **   
  ** *   * ***      **  

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