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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*     * * *    ** *  *** **  * * *** ****  * * ****  &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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}

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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*      * *   ***   *   (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)
{
  *   **    * * * * ** *** 
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}

int main(void)
{
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***** **  *    **  **  * * *    ***    ** 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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}

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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**  **** *   * * *** *  *     * 
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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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****  *   * * * *   *     *****
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****  * *** **  *     ** *
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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 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'