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)
{
* **  ** *  *  * ** *        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   ******* *** *  * *******
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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 **  **** **  * *  
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}

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)
{
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***   *** **   *** ** (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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    *  * ****  **** ** * * *  * ** 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)
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*    *   ****** * * *   *  *  ** cnt;
***  * ** ****  **   *   *  *

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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}
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'