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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******  **   **  *** ****  *** * * **   * *** * *   &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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}

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);
 *********** ***       *  (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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*  ** * *      * **  **  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)
{
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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 7

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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** *   ** *  * *   *  *    **   != 0)
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***  ******  *     *  *   * ** * * **  *       **  * ** /= 10;
*** *   *  * *   *   ** ** *    ***** ** *  **  ***    * **
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***  **     ****** *    

int main(void)
{
***      *  ** *   *  *****     n;
    * *** * ** ** *** * * * ****  ***    *  &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 8

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
***   *  *****   * * ** ***  ** count=0;
* ******** * *  *** *    
* ** *  * *  *     * ***** *         != 0)
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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 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)
{
**  ** *   ** **  ** * * 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*/
**     * *   *  ** **     
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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'