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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}

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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}

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)
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for (divisor    * **    *** * * **    
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return true;
}
int main(void)
{
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***  *    * *  *   **** * ** * *   *  *  &n);
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* * *  ** ** *   *   * **  ** *** ** *   ** *****   *  *  ** ** * 
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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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**   *     *** * * * *   **  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)
{
****** * *  ***     *  * *  **    count=0;
 **  * **  * ** *  * *** *      != 0)
*    **  *    **  *** 
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*   ***  ** * ** ***** *  * *   *  **  *  * **** **  * ** /= 10;
 * * *  *** ***    **  *
*   *      *** **   **** **      * 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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*   *** *** * *     ***   ** *   ** ***   **        * ***
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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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* *        ***   *         *
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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'