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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**** * **  **  * **   **  *  *  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)
{
***    ** ** ** ****   * n;
**   **  * **  *   **  *** *   *   &n);
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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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*     * **  **** *        * **** ** 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)
***  *  *  *** * ** **  * *
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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 7

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