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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***    **          ** *** *  **   ***       * ***  *  *  * *
 ****  * ***    *** *   ** * *  **  ***  * *  ** * * * /= 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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 * *  *  * ** *   * *  *  ***** * * * 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;
  *** * ****     ***
**    ***     **  * *** ** **  
***  *    **  *  *   ** *      * **
}

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)
*   * **     *** ***
 ** *    *   *     ******   *     ** * * *****  *     * **** * 
 *     *    **   *  * ***   ** *    *      *  ** ****  /= 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 7

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

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