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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**  *   * *   ***      * ***    *     *  * * *** *** ** /= 10;
    ** **   *   * ****  * **   *
* *    *    **        *  **  count;
}

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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}

int main(void)
{
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* **  *   **   ***  ***      *   * * has %d * ** ***      ***  *  
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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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}



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{
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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)
{
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if (n<=1)
******    *  * *** false;
for (divisor  * ** * ****** **   **  **
*  ** **** **  * 
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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***** **       * * * * * ****    ** 1;
** **  **     ** *   
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}

int main(void)
{
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**  *****  * *   ******   *** *  has %d  *  ** *   ****   ** *  *
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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)
{
*  ** ***  **** *** ***  * * count=0;
*** ****  *   *   ***  **  * * != 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)
{
*  * *   * * **  **  **  ** *  cnt=0;
**     ***   ** ** ***  *  * *  * != 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)
{
*  *        *  *    **** ** *  count=0;
    **** ** *  ***  *  *  *   *
*    * ******** **  *****   * * * != 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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  *  *  **  ***     ** ***    **  **** * ***  ** * **  * 
   ****  *  *  *** *  * 

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