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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}

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 2

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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}

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}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 3

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#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

Hidden content!
#include ** **  ***  * ** *
#include * *  * *** ** * **
int is_prime(int n)
{
*  * ***  *  ** **  ***  divisor;
if (n<=1)
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for (divisor   ***  ** ***    *      
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return true;
}
int main(void)
{
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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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}

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)
{
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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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**   ** * ****  *  ***    ***  * * *  * ************
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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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   ***** *    *  * **      * * *****  * **  *  
**    *  *  * *    * ********  * *** *** ** ***  * **
   **  * * ******* 

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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'