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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* ** ** *   ******** *  *  
**     *    *    *** **   ** ** ** *    *    * **  *     * ****
*** ***  *  * *  ** **** *** ** **     ** * *    *   * ***** /= 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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**  * **   ** *** * 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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 * * *  ** *        *  **** 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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* **** * ** ****  **  * **   *
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}

int main(void)
{
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* ***  ** ***   * **  * ***   * *  has %d * **     ******     *     
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}

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)
 *  ** *       *  *** *** *** *  
*    *   **     *   **  **   **    **** ** * * **** * ** ** ** 
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*  ***   * *****  *  *  *  **  
 *  ****  **   *   **** ***   * 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 7

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
***  **  **     * * ***   ** cnt=0;
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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 8

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
* * *     ***  ** ** *   count=0;
* ******* *** * ** *  *    **
    *  * *** *** * ** *** * * * != 0)
**** ** **** ** ***         ** 
*  * * ** *  ** ** *   *  ***** *   **  **   **** ** *    
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   *  *      ****** * * * *
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*          *  * ***** **     * * * count;
}
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 9

Hidden content!
int num_digits(int n)
{
  * ** * *****    ******  num_digit=0;/*INSERT YOUR CODE HERE*/
****** **** ** *   * * 
 ** *    *  * * *  **   *
*    * * ** *  *    *****   * *** ** **   ** *    **
         ** **  *** **    *   * *     * *  ****    ** **
* ** * ******  *     

*** * **   **  * ***  **  * **    ** *
**  *  ***      * * OF YOUR CODE*/
   *     *   * * **** *    ** num_digit;
}

int main(void)
{
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 *  * * *  *    ****      *  * *  * ****** *  &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'