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;
* * ** ***   * *    **** * *    ** != 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 2

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
***  *      ** **    * ******  i;
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    ****   *  * ***   * *   ** ** i;
}

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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*** *   ***  ***   ** *  *   * 1;
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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)
{
    ** *** *  ****   * **  *  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)
{
****    **** ** *  ** *  * * count=0;
 *  **** *  *     ****    * ** != 0)
  ** ** ** *   **  **** *** *
***    * ***  * ***   *  ** * *  **  ** * ** *   *    *
    * ********    *     *** ** * * * ****  ***   ****  /= 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 7

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

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 8

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