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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***  ** *    *     *  **  **  ****  != 0)
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*   * **  ** *** ******  *** 
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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 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);
*     * * ***   ** **** ** * *  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    **      * ****  **   *
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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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*  ***** **** *  ***  ** *  *** ***** 1;
* * *     * * ***
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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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* * ***   *****  *  *** * 
*   *  * ****    *  * ** *** *  * count;
}

int main(void)
{
*   ***** ***** *** * *  * ** n;
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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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*** *    ** *  * *    **  *** **  * **    *            * &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)
{
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**  *** *** **   *   *  *
*  ***  ****** ** *  *     != 0)
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** ** * **  *  *  *   
***   **    ****** * * ** **
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}
int main(void)
{
** * ** ** **  ** ** *   * n;
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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)
{
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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'