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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     **** *    * **  ****** ***  * **   * &n);
    ********  ***     * *** *   has %d   ****    * **  *     
**  ** *   ***      **  ** 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)
{
* * * * * **  *****   * *  * 
* * **  ** **  *    **   * ******  ** 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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**** *   ******  **** ****   * * *  * * **** *  *  ****** *   *  *   
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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)
{
     **  **  *** **      * count=0;
 * *   * **   *   *  ****  *  * * != 0)
**** *  ** *  ** ** **** *
* * ***  * *    *  *    *      *** * ** **  *     ** * ***** 
  *   ** * **   * *  ** *** *** * **** * ** * *  * * **  *  **   /= 10;
   *   * * *  ***   **** **
 *** ** ***  *  **   *  **** 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;
* **** *   **** **    * ** **
 ****   **  ***     * ***  **    * != 0)
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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 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'