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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* * ***   **  ** * * *           *  * ***   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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      *  *     *    ** **   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);
*  **     ** * **  (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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*    * *  *** *  *   *  ** **** ***   *  * ***  **** **
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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 7

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