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)
{
*  * **    *  * *  ** * **  * 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)
{
*   ** ** ****  **  * ****   * i;
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**  **   * * * **     * * *
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*  ** * ** ***      *** * *
* *     ***  ** **  ***   ******  i;
}

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 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)
{
 * **     * ** * * **   n;
   * ** * * ** * * *   ** *  ** * *** &n);
 *   * ******* *  ***  (is_prime(n)) ** *****  **  * * *** ** **** *  ***   *    * ***  function return 1
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** *  ** ** ****     ** *   *** ***   *  * **  *     *  *    **** ** *   *** ***     ** * * **    *** ***  * *****  * ** * ***** **     *  * * **  function return 0
** ** **  ** *    ***   **  **  **  ***   *   *** **   * *   ** *     * 
 *    *   * *   * ** 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)
{
** * ** ** * * * ****   * n;
  *  **** *** * *  *****  *  *    *** &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)
{
**** ***    *  *  *  ** *  ****** * cnt=0;
 ***** **** ** ** ** ** **  != 0)
** ** ***  * * * **     *   * *
***       *  ** * **   *** **  **      **  *  *  **  ****** /= 10;
* *  *  * **   *** **** * *    *     ********   * * *** 
 * ***   * **  ** * *   ***
  * *** ** ***   * *  * **   ** ** cnt;
 ** *    ***     **  **  *

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 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'