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)
{
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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 3

Hidden content!
#include *   *   * **  
#include     *****  **   
int num_digits(int n)
{
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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;
* **** ***** ** ****  * *
**  * *   *  *  *  *   * 
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}

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)
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**** * * **** *** *  ** * *     ***   ******* * * /= 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)
{
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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 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'