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)
{
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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 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;
 **  *** ****** *  *   *    * ***   **  * &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'