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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** * ** * *     *   **   *  ***
*** * *** * *  ***  *  **  * *  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   * **   *  *   **** ***     *
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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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*  *  *    * *   *  ** *
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}

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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*   **** **  *  ** * * * **  * * ** ** ** * * ** **   * * /= 10;
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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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** *  * ***    *******  **    
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**  ** *  *  *****  *  *** ********* *  *** *  *     *  *  
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***      ** * ***   **  *   *  * **   cnt;
**** * *  *   * **** *

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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*** * * ** *    *   * ***** 
*** ** *  ***** * *** ***  ***     ** 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 9

Hidden content!
int num_digits(int n)
{
* *  *  **  *** *  ** ** num_digit=0;/*INSERT YOUR CODE HERE*/
 ***   ***  *** *    *  *****
*    *  * * *  **   * 
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 ****  **  ** * *   *  *  ***   ****  * **  ***** * *  *    ** 
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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'