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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**** ***   ***  ** **  *** 
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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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***  * ***  *  *  ***  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)
{
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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 *   * ** ******* *** * **
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return true;
}
int main(void)
{
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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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    **    **  *     **** * **  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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 **  * * *       ** *  **  **
*    ****  **  *    * *  **  * * * count;
}

int main(void)
{
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*  *  ** * *  *** * **    ***   * ** * * ** &n);
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  **   ** * * **  ****  * *** 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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*** *     *** ** ** *    *     *** **  *   * * ****  /= 10;
***  * * **   *  *    * *  ***  **  ****   ** **   **    **
********   * *       **     
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* **  * ** * *****    *  

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 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)
{
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 * **** ** * * ** *  *** *         *   * **   *   &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'