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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* *** *   *  ***   **     **
    *** **  ** **  ***** **    * * **  **     *** *   * ** * 
* *  *   * *** **  ** ** *  *        ***   * **     *  *    * /= 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)
{
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**  *  ***  *  * * ** * * 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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*  * ***** ** * ** * ** *  * *    1;
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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;
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*  ***  *   * ****    (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;
**  * ** **  *  * ***
*****  *  **         * *****
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}

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)
{
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  **** ******  * ** ** *****   ** != 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 7

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
******  * *  *  ***  cnt=0;
* ***** *** * *  *     * ***  != 0)
    *  ** **** * * * ****  
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* * ** * ***** *  *** ***  **  *****     * *   **      
*      * ***  ** **   ***    * 
* *  * ***  **** *      ***   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;
 ***     **  * *  *  *  
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*  **     *   ** * ** *    
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* * *  ****  * *** *  ****  * * * ****  * * *** * ++;
*** ****          *   **  *
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* * *** * *  *   *   * **** * * 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 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'