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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}

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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 ***  **   *   ** *  ***  *** *   * 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)
{
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** *  *** **  ** *   ***   *** *   *  != 0)
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******** *  *  ** **      *     ** ****  **  * *  /= 10;
* * * *   **  ** *********  ***  * *    ** ******  *
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  **  **   *  *  **** ***  * ** cnt;
 * ** ***   * ** ** *     *  *

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 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'