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)
{
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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)
{
* *  *      * ***** *  n;
*   *  ** *     **  ** * *** *  * * *  &n);
 * **  *    **   *****    **  ** has %d  * ** ****** ** *  *** 
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}

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)
{
***  * * ** *   * *** * ***
***  **    *** **  ***    * * 1;
** **   **   *   * 
***   * *** *  * ***** *  * *  
*   * ** *** **   **   **  *** ** *   
}



int main(void)
{
*  *   * *   * *  ***  n;
* * **    **  *     ***** ** * ** * ** &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)
{
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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)
{
  ****   ** **   **  **   ** 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'