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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  ** * *    **   **  * * ** ***  *  ***   *  **** **   *  *  /= 10;
  *     *** ** * *   * ** 
   * *    *  * *   * **  *  * * 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 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  ** ***** *   *   * * ** ** 
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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)
{
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*****  **  ***   ****  *  * **   ***  *** &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)
{
***    ** ** * **  ** **   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)
{
** * ***    *  ** *** * ****  * *   cnt=0;
  *** *   *  **   ** * *   *  != 0)
  *    * * *   **     **   ** 
 * * * ** **     * * **   *******   *** *    ** ** /= 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 8

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

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