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)
{
***  **   *   * **** *     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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 ***    ** *** **    ** * **  **   *** * &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)
{
* *** *    ******     ***  
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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: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;
  * ***   * *   * ****
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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)
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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 7

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