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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*   * *****  * ****** *   ** * *** *  ***** * ******** * /= 10;
  *** **  ** *   *  * ** * ** *
 * **  * * *** *****    *  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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* **   ***   *    **** *   ****  * has %d *    * **    * * **  * 
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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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{
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* ** *    *      *    ****     * has %d   ** **** *****    *   *  * 
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}

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)
{
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if (n<=1)
* *  * ** *   *  false;
for (divisor *  * * ***   *  *** ***  *  *
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return true;
}
int main(void)
{
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*  **   * ** * **   *    ** **  ***** &n);
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}

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)
{
** * **  ********  **   * count=0;
* ** ***  *         * * **  ** * != 0)
**      ** *  * *  *   *  * *
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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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*   *** **   ** * *  **   *
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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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   *   *  * ** *  *** *     ** **    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'