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  *  * ****     *  *     *
 * * * *     *** ** ** * * *** **  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  ** * *  ** ***** ** ** **
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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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*   **   *      *   *** **  (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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**       * * * * *   *    ** * 1;
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* * * ** * *  **   *** * *  *     ***
}

int main(void)
{
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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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}

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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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 8

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 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)
{
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  * * *  *** ****** **  *** * * * ** 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*/
* ** *****  * **       * * *
*    * ** ** * *  *
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     *  ** * ***  *  ****      * * *  * ***   
*  *    ***  *** **** 

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