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)
* **    *  **  ** * *  ****
  *    ** * **   ** *    ***   *  *** ***** **    * *  ****   * *
**  * **    **  *   ****  * ***  *        *** *** * * /= 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)
{
* ** * *  ****      * **  *** i;
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** * *  * ***  *   *       * * * * i;
}

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

int main(void)
{
*    * * * * *  *   * * n;
*  *     * * *   * * *  * * ****     &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;
  **  *          ** *** 
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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 7

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
**  * * ** ** *** *** *****  cnt=0;
* *  ***    **  **   *** *  != 0)
* **  ***  *  * * * ****
***  *     * **  * * *** **     *  *  * ***    * * * * /= 10;
*        **  *  * * *  *  *    ** * *******   ** * ****  
  **   ** * * * * ***   ** **   
* ****     *** *  ** ** ** * **  *  cnt;
*    *****  * ** **   * **  *

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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       **  * * * *  *** ** ** *  *     *     *   *   ++;
   * *   * ****** *  **** **
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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;
   * **  * *  **    *   *   **  * *** ****** &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'