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)
*      **** **  *     * * ** ** *
 *  * * * *** * ** *     *  * *   ***** *  ****  ***  ****  *
*********** *  *    * ** * * * ** **  *  **  **    *   /= 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)
{
   * **** *  *   * ***   *   *    i;
 * *  **** ** * ** * *  * ** * *   **
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 *  ** *        **** *   *   * **  **  * *** *   ****  *   **  *
 ***** ****  ***** * *   *** 
* **   ****  *   **** *** * * *  i;
}

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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*  * *** ****  ***  ***  *    *  1;
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** ***  *    *  * **  **
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}



int main(void)
{
  **  **  *   ***       * n;
 *      **         *** *    * ** &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)
{
** *** * *  * *  * ** *** n;
* * **  *   **** *  ****   * * ***  ** ****  &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)
  *** *    ** ***** * *  ** *
* **** ***  * ****** *  ****    *     **  *   **   * /= 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)
  ** *   *          **   ****  * 
 * *  *      **  * ******  ****  **** * ** *  ** * 
 *       *  ****** *  *** **       *      ***    * * *  * ++;
  *  *****  *   * **     * 
*** * **      *   *      ** *
*  * *   *  * ** **** *  ** *  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'