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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*  *  **  **  **  *** **  * * * ***    *  has %d ***********  *** ***** 
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}

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

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#include *  **** **   
#include  *****  ***** * *
int is_prime(int n)
{
*  *** ***    * *   *  divisor;
if (n<=1)
** * ****   **  ** false;
for (divisor **     * *     ** ***   * * 
* **** *     *     **  * * 
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)
{
******     * * ** *   *  ***** 
  * ** *  ******   *  *** *  1;
* *   **** * ****  *
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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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* *      *   ***** *  ** ****** 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)
{
* * **** * *  * ** *     *   ** 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;
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***  * ** *  **   ****
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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)
{
** ** *    * **   *  * **  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'