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)
{
   **** ** *  *    *** n;
**    *  * *   *  ***  *  * * *    * **  &n);
  *  *     * **   * **** *  * ** has %d * * * * **      **  
 *  **  *       * ***  *  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)
{
*  *  * ********* *    *  
*  * * *  * *  **    *    **  ** 1;
* * **  *  *   *  * * 
*  **   ***    *  *******
*   *    **  *  *  ***** ** * *   * 
}



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
**** * * ** ***** *** *** *** **   * * * **   **  **  ****      *  
***  * ** * * *      **   **   * *** * * *   **  * *  ** *** *** * *   ** *** ***    *      * *** *    *  *  * *** *      * *  **  *  ** *   ****  *      * * ** *** * * *  function return 0
*** ** *  **    *   *** **   ** * * **  ***  ****  *  *  *  *   ** **
** * * **  *    ***   ***  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)
 ******** ***  **   *
 * * **  *  ** *  ***   *******    *    ** *  *  **** * * * 
**  *   ********    * *   **  **** **   *** * ** *    *** /= 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)
 *    *  *  ****  *  ** 
   * **  * ** ***  *   * *** *** *** *  *  ***** * ** * * /= 10;
**** **   *** ***** *   *  * * *  *    *  * * * * *       *   * 
 *  *** ** * **  *  ***
  * ** ** * **** *******  * ** 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)
  ***  *   ***** *  * *  **  *
 * **   *   *** *     ** **  **** *      *      *    * 
**  ** * *    *   * **** ***** *    *  * * * *  *   ***    ++;
*  * * **    * *  *  * ***   **** 
*  ** * * **  * * ***** *
**  ****  ** *    ******  ** **   ***  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'