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)
{
* *  *** ** *** *****   * * n;
*  ** * *  *   *     * **** **  *   *  * ***** *  * &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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 * ***** * * *   *    *  *     * has %d  **  ** *** * **  *  *  ***
**    * * ***  * **         0;
}

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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* *  *** **  *   ** *** * * 1;
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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   * *  * ** * ****   *  
**  *   *  *  *  *    *** ***
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)
{
  *** *  *** * *** *****  * 
* ***   ***** *   *** **** * 1;
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* *** *****  *  *     *  **** 
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}

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

int main(void)
{
    *** *   * * *  **     * ****  n;
 *    *** ** ** * ** * ***   **    * * * *   *   &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)
{
 *  *** *  *   * * * *  *     cnt=0;
 *  * **** * *** **   ****  * * *** != 0)
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** **   * ** ** ** *   **
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***    *      **   ****  *  * *

int main(void)
{
*       **   *** **   ***     * n;
*** *****     ****** **   ** ******    ** *   *  &n);
 ***    ** *   *******    ******  *    ** **  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)
{
**   *          ** ** **   * count=0;
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*****  * **    **** **  ** *    != 0)
*   * ** *****  *   **** *   **
**  *     *    *      **** *  **  * ******* ** * *  **       *    * *
* *   ** ****** *  **    *** **    **  * **  **    ***   * ++;
*  **  ***  *   *  ****    *
*   ** ** ***** * * * *  * 
*****    **** * * ******   **   count;
}
int main(void)
{
*  ***  * *  ****  ** * ** * **   n;
******  *     *  ***    ***   ***    ** *  &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*/
 *      **     *      *    ****
 * * ***** * * * * **  
** **** **  *  **    *** *****   *** * *** *** * 
    * * *    *   * * * *** * ***    * * ***** ***  * **
 ***  ***   * * *  *  

** * *    * * *     * * *  * ** * 
*    ** **  * ** **     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*/
* *  ** **    *  **   * * 
**   ****** ** * 
****   *** ** * *   * *    **  *  ** * ** *  * *  ** 
 *  * ** ** *    *  ***    *****        ** *  * ** *
*******  *     ***

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