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)
{
 ***   ******  ***  *   * *  *  * 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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***  * * **  *   **  **    *   ** i;
}

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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***    *  ** * * **** * *     *    1;
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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)
{
* * *  * **  *  *  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;
***       **  ***  *** * *
* *  *  ** *   **     **  *
* *  * **  * * ***  ***   *  *   ** *
}

int main(void)
{
*   * * *****   **** * n;
*  **  ****   ***  ****       ***    &n);
***  * ** ** * **** * *****  * **  * 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)
{
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***   **    *  ** ***    ** * != 0)
* *    **  ***  *** ** ***** * 
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* ****** ***   ** * *  *  **  ** *** * * * **   ** *  ***  /= 10;
 *** * *****   **  **  *     * *
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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 7

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