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)
{
*  *** *     *   **  * ** * ** n;
* **     *        ***   * * ***  * *        **    &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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* *  * * ***   ** * * ******** *  **  ** **** * &n);
 * ***  * *     *     *** ***  *   has %d ** ** * * **  **  *  *
    *  *     *   **  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);
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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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 **    *   ***    *   **  *   *** 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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**  ***** ****  *   * ** != 0)
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*** * **      ******** * * *   * ** * * ** **   *    ****  *   
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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;
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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 8

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 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'