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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* **    ** *****  **      *   ** 
*   **   * **   * *    ***** * * count;
}

int main(void)
{
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*  * *   **  **  **      ** *      ** *  *  *  has %d *  * * **  ***  *** 
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}

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

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)
{
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  *  * ******** ** *  ** **   * * != 0)
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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 7

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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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 8

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