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)
{
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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 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  * **  *  ** * *  *** ***
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return true;
}
int main(void)
{
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**   ** ** **** ** * (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)
{
  *** ****  *** ***** *   *
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*  **  **   **  **
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}

int main(void)
{
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   * ** *  ******* * ** * 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)
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*  **  *     **** * * ** * ****** *   *   * * **  **   * ***  **
*  ** **  *** ***   * * * ****** *** *** ****    **** * /= 10;
     *****   * ** * *  
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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 7

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

* ***  * * *  *  *** *  * *  *  **  ***
**  * * **   **   **  * 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'