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)
{
* ** **  *   **      *  ** * * count=0;
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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 2

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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}

int main(void)
{
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* ****      *****   ** ******  *** *    has %d ***  * ** *** *       
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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 *  *** * *  *****  ***  
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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)
{
***   **    ** *   **  
 *  ** ***    *     *   * ***   *  1;
*  * * *****   ** ** 
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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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***  **    * *   ***  ****   *  * * * != 0)
*    *  *** **** *** ** * **
   *    ** ** *** *** **  *** ****** ****** **  *  ***  ** * 
**   *  **    ***     **    * *  * ** ********   *  *   /= 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 7

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

   *** ***   **  *****  *  * *** **** *  ****
  ** *  **   **** ** *  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'