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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*** *   * * ***   * ***   *  * 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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* **** *   ** **** ** **** **** *  *  *   ** * **     *   ***      
   ** * *   *  *   ***    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;
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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)
{
   *       * *  *  *      * 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)
** * * **   ** *    * *  *  *
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 ***      * ** * **** *** **  ** ***  * *** *** ** * ** * ++;
*   ** ** * *         
**  * * *  *******      
****     ****** *  * ** ****** ***** 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'