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)
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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 2

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
    *  *  * * *****  * * *  i;
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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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*  ***       *** **  
*  **   *   * ***  * *    
*** **  *  ****** * ****    * *   * 
}



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
*   ***  *  ** *  **   *   **   **   **     * * *  ** **    
**  *  * * ** * * **  ***   ** **  * *  ** *   * *  *  *   *** **  *** *  **     *  *  * *     * *****  ** ****** *** * ***  *  ********   **** *  * * **    * *   function return 0
*  * * * ** * **   **** *** ** **  * * **   *** **     * ** ** * *  *   * 
*  *** *     * ****  * 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)
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 *  * ***** **  **  ** * * **** *     ****** /= 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'