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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***       * *  *  **       * ** *      * ** **  * ***
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   *    *** * ***  **  ****  *
**     ** **  * ***   ***  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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* * *********   * **** 
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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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** **   *  *   * * *** ****  *    ** &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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**  * **** ***     * *     ***********  * &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)
{
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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 7

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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*  *  ***      * *  **   ** ** != 0)
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    *  * ** **   ** ** * ** *   *  *  ** *   **   **** ***
  *  *  *   * * ******* **    
* * ** * * * ****  *    ** * ***    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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*   *   *      *  ****  *
       *****  *  *  ****   **  
    ** *    *  **  ****  ** *****  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)
{
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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'