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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* **  *   *    * *      *  **  
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* ** * *       ***   *   **** * * * i;
}

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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****    * *  *   ** * **  * 1;
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}



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