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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*   **  * *   **  * ** * * 
  * ** **** * ** * *  ****   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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}

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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*** *  * ***  *  *** *****  *  ** 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    *  * **   *    * * ** 
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return true;
}
int main(void)
{
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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)
{
*** * * *  *   ******  ******
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***  *       *      
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}

int main(void)
{
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*     * **       *  *   ** *  has %d * *** *   * *   * * **   
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}

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)
{
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***     * **   * **  ******  *  ** ** * * &n);
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}

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)
{
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  * *** ** * *** *** ** **   **  *  != 0)
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**** *****  **  *****    * *

int main(void)
{
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*****   ***  * * * ** ** *   * ** *** 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)
{
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** *    *  * ****   * * * * *     != 0)
** *   *   ***     ** * 
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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*/
  * * ** * ** **   **  *
*  ** *** *  *   ** **  **
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 *      *     ** **** * *   ** * * * *  * *  ** ** ** *
 * *   **   **** ***   *

 *  *    ** *** ***  **** *   * *  *   *
  ** *   ** **     ** *  ** OF YOUR CODE*/
*** * ** ** *  *  ** *  num_digit;
}

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