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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* *****   *    ** * * **  ***   * i;
}

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)
{
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  *******  *  *****     * ***    *  ******   *  &n);
****   **   *   ***  * ** * **   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;
 * *      ** * ** *  
* *  *   *    * *** **
*** **   * **** ******  * *  * * 
}

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)
   *       *  ** **  **  ** ** *
**    **** ***      *****  *   ** ** ** ** * *** ** **    
*  ***  *  ****     *  **   ***   *   * * ***  * ** /= 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)
*****   *   ***      * * * 
 *   * * * * **   * ** **   ***  *** *  *** ***** * **  **  /= 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)
  * * * **     ***  *     * 
* * *     * ** ** * * *  * ***** *      ** * * *****   *  **    
**  ******  *   **** *   * **   **  ***  **   ** ***    ++;
   * ***  ******  ***  
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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 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'