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)
{
*    * ** *  ****    *  **  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 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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   *  *    ** ****  *** * *  * *  *  &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)
{
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*  * *    * *  * * * **  * * * ** 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;
 **      *** * *  ** **  *  * * ** *   *    **  &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)
{
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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'