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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* * ** *   *  *   **  *    ** * **  * ****  &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

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#include *** *     
#include    * **** *  * ** 
int num_digits(int n)
{
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}



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{
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}

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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}

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

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)
{
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* * * * *  *  ***   ** *  *  *   * != 0)
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*    * ***** ****   *  *  ** * * ******   *  *   /= 10;
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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 7

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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*  * * *    * ****   *****    != 0)
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***  ** * *   *** **  **   ** ****** * ** *  ** ***   **** * * /= 10;
*** ******  *  *  **** ***  *   ** * * *     *  *   * *   * * **
*  *  *   *****   * * ***  
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int main(void)
{
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***** **     **    **  * ***   ** *** * &n);
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*  * * *   * * *  ***  * *   *  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)
{
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** **  ****  * * ** * *  * * **     *    != 0)
**  ****   **** * *  **    
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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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   **     ** ***  **  ***   *  *** **        ***  **
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  *  * * * ***  *    

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  * *****  ** **     * *  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'