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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* *  ** *** **   **** * *     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)
{
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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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*    ****   * * * * * * *    * * *  ** *** * *   *     ***
* **  *     ***  *  ** ****  **   * ** *    * * * * /= 10;
* * * **  * *   ** ***  **  
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}

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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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)
{
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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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  *    * **** * **    *****  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'