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)
{
* *  *** **     ** *  *   **    n;
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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 2

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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}

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 3

Hidden content!
#include ** * * ***   ***
#include  **       ** * 
int num_digits(int n)
{
** * *  *    *** ***** *    *
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*** *  **  ***   * * 
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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  * *** *  ** *  **   * ****  
**  ******     *  * **** 
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;
* * **  *  ***  ** *  
* *    * *** * **  * *** 
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}

int main(void)
{
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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)
{
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**** *** * ****** *   * *     ***  != 0)
* ** *     *  * **   *   
** *   **  * * ***  *  * *** *****    * * ****    *  * ***
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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 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;
  * * *******      *   * *** 
 ** ** ** *  ** * ** * ** * ** *    ** != 0)
**     * *    *    ***** *
  **    *** ****     ** *  * ** *   *  * ** ****   * * 
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*         *     *  * *  ****  *
*** *        *    *** *
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}
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'