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

int main(void)
{
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* **     **    *   ** **  *  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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** *  ****** *     * **  
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*  *     ** * *    ******     * ** *   *  **  * ****  *
*** *     ** ** *     *  ***  
*** * *    **  * *  ***      *  *  cnt;
***    *** *** * * **  * * **  *

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;
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}
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 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'