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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*** *  **  * *  **   *       * * ** != 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 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

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#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)
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for (divisor  **** * ** *  ** *** ** 
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return true;
}
int main(void)
{
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*** **** *       * * ** **   ** ** * **   &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)
{
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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: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)
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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 7

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