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)
{
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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)
{
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**** * ****** *  *  **** * *  i;
}

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 3

Hidden content!
#include   * ** **   * * **
#include ***    * *   **
int num_digits(int n)
{
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}



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

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

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 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)
{
******* ****     * * **  *  *  * n;
*  *  ***** **     *  * **** *   ** **  *** **    &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'