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 **    *  * ** *   *   * *   
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}

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 * **  *   ** ***     **
*  ***** *  * *  ** * ***
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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}

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

int main(void)
{
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****  **  *** * ***       **   *****  ** **         &n);
***     * * *  ***  ***   * *    ***   * has %d ** *    **   ***   * 
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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)
{
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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 8

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 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'