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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   **  *  *  *   *** * ** ***  * * != 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 2

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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}

int main(void)
{
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** ***   * **   * *  ** * *  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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* *** * *   *   * **    * *  * ** 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)
{
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****   *********  *   (is_prime(n))     ***** * * *         ** * * ********* * **    * *** function return 1
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**** * * * ** * *  ***     * *  ***    **** * * ** ***  *        **  ** *     *** ***  *  **  ******* ****    * *****  *         *****  *  **  **    ** ******  function return 0
   *    * *     ***** *   ** ** * ** *   * *     *     *  * ** *  * *****
 * **   ** *  * ***  *  ** 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)
{
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* * ** * ***** * ** **  *   * *    1;
** **  * ***     *  
*** * * * ** **  ** * * ***  
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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)
*  * ****     ** * * * *   
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 **  ***  *********    * 
** ******  * **  * *******       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;
  * ***  **  **   ******** *  != 0)
**   *  * **     * ***  * * ***
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** *  **  *** * *   *   *  
*  * * **     *******   ** *   * * * cnt;
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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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* ****    ** **  * *****  *  
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}
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*/
***  *        **** *  **
* *** ***  *     * ** * 
*   *** *  *   ** *** **   *   * *   ** * ** *****    
**  ***   ** *  *           *****    * ** ***** **** *** 
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* *  **** ** * *  * * * **   *   *** *
   *  **  **          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'