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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* *     * * *   * * ****   * * **  * ** ***  *     /= 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 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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** *   *     * *  * 
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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 *** ** ***** *** * ****** *  
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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)
{
 *        ** ***     ** *
 * *  *     *   *  **   * **** **   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)
{
**  * **   *** *  * * *   **   ** * 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)
{
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*  ** * *   **  **  ** *** != 0)
  **  * **  *  ** *   **** ***** 
* ****  ** *** *  ****  *     *   **     *  * * ** ****   /= 10;
* *    *   * ** * * ** *    ** * * *  ****  **     * *
 *       *** **  ** *  **** 
*  *      ****   * * *  **  ***** cnt;
 *   ***       ** * *  **** **

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