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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}

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 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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  * *  *** **  **  * *  * * 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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*  *  *** * ***    *  *  *  (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)
{
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**  * ***  ***      
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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)
{
* *  *   **   **** ***     * count=0;
** *     *  ***** * * * * *    *  != 0)
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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 7

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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** *    **** ***** *   * ****  ****  **    ** * &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)
{
 *** ** *** *   *  *     ** count=0;
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*   *   **  ***   * *  *  * * * != 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 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)
{
*      ** ** * * *  *    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'