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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}

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

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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*** *   **  * *    *****   * 
*  *  **    * **  **   *     ** ** * *    * * ** ***   *** * * ** 
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*   *    ** ** *    **  ** 
** *** *****    ***   * * * *  count;
}

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 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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*     *  *   ** ** **** **  ** **    * * &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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}
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'