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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*  **   * ***  *   * **  *  * ** 
* *  * * * * * **** **  ****  ** * *** *   * ** 
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  **  * * *  ** *    **
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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 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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*  *  *     *     *** ******    ** ** * * **  &n);
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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;
*  *** ** ***  *    **
**  *** * ** * **  *  **
*  ******  *   * *  *  *** *  * *** * **
}

int main(void)
{
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*     **   * ***  * *  * **  **   * ** *   &n);
* *  ******  * * ** *  * *  **    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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 *  ****      **  *  *** 
******   ***  *** ****** *    **  count;
}

int main(void)
{
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* ***  **      *** **  *      ***  ** *  &n);
** **  *  *  *   *    **  ***** * **  *  has %d **** ** *    ***    * *
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}

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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 ****  ** ** **  * ** * **  *  * *** 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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   *       * *     * *  *  * * *
**    ** ***** * **  *   ** * * **  != 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*/
* *** **  * * *  * ***    * 
* * ** ***  *  ***
*  * **** ** *** *  ** ** * * ** *** **  **
* *   *****  *       *** *  ** **** ** *  ** ***  * *  ****
 * *** **  *** *** * 

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