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;
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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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}

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)
{
** *   *  ** * ** ** ***  * 
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   * * * *  **  *
*  * ****    ** * *** *
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}

int main(void)
{
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*  ** *   * * *** *  *****  ** * **  *    &n);
   * *   * ****   **** ** ** *   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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     * * *  **  **   *  **   *  **  * * **   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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*   *  *** **   ** 

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)
***   ** *    **   **      * *** 
*   **   ** *   ***** ****  * ** *   *  **  *** *** ***    
***   * *   ******   ***  *  *  *  **  ***  * *  * * *    ** ++;
*** *  ******* *  ** *  *  
****  ** ** *   *   *    **
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}
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*/
 * ***    * ** *** * *******
   *    *** *   ** * * 
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*** ****    *  ***  

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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*/
**   ***** *  ***  *  **    *  
* *  * *  ******** *
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*   *   **  * **  **   ***  *****   ** **  * **
* * * *    ***   * **

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