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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*** *    **** *    **** *  *  != 0)
**  * * *  ***** *** * 
*   *  *** ***** *   ****** * *    ** ** * **   *** * **  **
 ** **   ** **  * ******  * *** **  **** *  * **   /= 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 2

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 3

Hidden content!
#include *    * *** 
#include   * * *** **  ***
int num_digits(int n)
{
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***   **** * ** * 
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}



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

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)
{
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  ** ** **  *   ****   * ****  != 0)
 *  ***   * ** **  * **** ***
** **  * **  *** **   * *** ******** ***   ****        **  
  *  * * ** **  ***  * ** * ***   * *** * ***  *  *** *  *  * /= 10;
**  * * ** *  * *  * *  
* * * ** ** *** * * ***  ***   * count;
}

int main(void)
{
  ****      **  *  ** *  ** *  n;
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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)
{
   * * * * *      *   *** ** * cnt=0;
*  *  ** *    *      *   ** * *   *  != 0)
* *  * * *   **  * *   *    
   ***  ***  * * **  ***  *     **  * * * **  * * *   * * ** /= 10;
**   *** ****** *   * **  ****   * ***  ** ** * * *
** * * * ** **   *** * ** * 
  *****  *  *     *       **  ****** cnt;
**     * * * ***   *  ** 

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;
 *  * * ***  * * * * * *
***        *  **** * * * *** != 0)
*** *** ***     * ** * ***   
****  *   * *    *  **  *  **** *        * ** * *    * **
* ** ****  * * *   ** * ** * ** **   ***  ** *  *  *  ++;
****     ****** ****   * * 
 **  ** *  *     *    ****
 **   ** **  ** ***** * *** * * 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 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'