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 ***  *  * * ***   *  *** 
* ***  *  **   *   *  *  *  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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*  *  *  *  *  **  * *****   *   ** ** &n);
***  **   * **** * *  *   **  has %d      ***  ***   ** ****  **
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}

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);
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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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}

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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**   ****  *** ** ** *  * * * ** ***     **   ***  ***   *   
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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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**     * * * * *   * *  ***** **** * != 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)
{
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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)
{
** *   * * *    *   **  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'