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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}

int main(void)
{
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}

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    * * * * *** ** * ***** *
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}

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 *     ** ** ***  **** *****
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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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**** ** * *   ***  *** **   
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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: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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* *** ** ** ** *  ****  * * ***** ** 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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*  ** *  * * *** *     *  *    *  ****   ***** *  **      /= 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)
 * * *  * *** ***** ** ****   
** ****     *     ***   *      * **  ***    ****   **** *
*  *****  * * * *   * ** *     *    **** *  *** ** *** ++;
**  * *  ** ***    **  ** *  
 **   *   ** * *** *  *     *
* *  ***** *** * *****    ** ** 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'