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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** ** *   *  *    **  * *  * != 0)
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 * *   **   *  *  *  ** * * * 
** *   * ***  *****   **   **  count;
}

int main(void)
{
* *  *   **  * *   * *     n;
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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)
{
* * ** **   * **  *** *  ** i;
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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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*  *  **    * *    **
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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 *  * ***    ** *  *******
* **    **   * *  *****   
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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 ** * *** **********   *  *  *  ** 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)
 * *  **   ****    ***  *
*  ***  ** **   *  * * **** **   * ** *       * * *  
**  ***      ********  *  ***    *  **    *   *  * **** /= 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 7

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

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 8

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 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'