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;
 * *   *  ** ** ** * * * * ** *    != 0)
* ** *   **    ** *  ** 
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 *  ** *  * ******* ** **     * * ****** *  ** *****    /= 10;
   *     ** ** **  ****    *
 ****  *** * **  ** ****** ****  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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********* **** *  ****** * ***   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)
{
* * *       *  *      *    * 
* ** * **   * ***  * **   * * ** 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: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;
*  ***  **   **** *   *
**  **  *  *  *   **   **
    ** *    * * ** * *    **    *  *
}

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)
* *     *   * ***   *
    *   **  * *       **  *      *** **  ***    **  *** *  **  * 
***  * **  **   ****     ****    * **** ****    **   /= 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 7

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

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 8

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 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'