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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 ****   **  ** * **  *    
*  * ** * ****    *** ** **  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 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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*   *****  ***  *     *  *  **** *  &n);
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  **  *** * * *  ****      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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* * **** * * ** **** *
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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)
{
****  ****  * * *  *  * * * *  count=0;
  *    ** * **** **  * **   *** * * ** != 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 7

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

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