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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  * *         *  * *****   *  *** * *  * *   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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* * ***  *    * * * ** ** *   1;
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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)
{
*  *** ** **  *    *****  
*   * * ****   ******  ** *       **   1;
** ***   **** *
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}

int main(void)
{
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*  ** ********* ***   * *** *    * * * &n);
***   *** **   ***** *  * *** *  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)
{
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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 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;
*  **   *** *   *   * **  * 
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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 9

Hidden content!
int num_digits(int n)
{
**      * * ** * **    num_digit=0;/*INSERT YOUR CODE HERE*/
   ** **     *   * * *** * *
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**  *  ** * ** ***   *  *  ****   *** *  * ** 
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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*/
    ***     ***  * *** *   *
***    *      * * 
 **** * *  * **    ** ** * *** *  *  **   **   ** **
** *  *** * ******   *  *** * * *    **     * *** **
 **  *  * ****  ** *

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