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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  ** * * *  *   * ** * ****  * **
* *** **** **** * ** *    **** 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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* *   *      *     * *    ****      ***  * &n);
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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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**  ** **  * * * *  * **  **  *** *     &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)
{
* **  *  * **** **  * * *
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 **  ***    ***** * 
*** *  *****   **  * ** *
** * ***   *   ** *   *   *  *   **
}

int main(void)
{
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**   * ***    *     * * **********  &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)
{
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*** * **  *** ** ***    **  ****  *  != 0)
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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 7

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

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*/
***  *** * **  *  ***** 
  *  ** ** * *   *    
* *** *****   ** ***** ** ******    ** ** * * ***
  **  * *  * *  ** **** * *  * **  ****** **  **  *** 
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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'