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)
{
*        **     *  ***    * count=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 2

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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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 3

Hidden content!
#include **  *  *   * 
#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: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)
{
* *** ****  *  * ** *    n;
  *     *  ***  **    *  * **  ***     **  ** &n);
* ***  **** *** ***   ** (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)
{
 * *****  *  * **  ****  ** *
** * *    ***** *  *****     *** 1;
* ** * ******    *
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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)
{
* *  *   ** *   **     ** * **   count=0;
*** **   *** *  ** *    * * **      *  != 0)
**    *    ** ** * *   ***** *
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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 7

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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** ** * *  ***   * * * ** **    != 0)
*    ** *****  **   **** *** **
*  *** *  **  * * ** ***          **     * * ***  *   * ** /= 10;
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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)
{
* ** *  *  ** * *  *      ** *  ** count=0;
 *  ** *** ****   *  *  *
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***** **   ** **  **  ***** * 
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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 9

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

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