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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*****    * ** ****  *    * *****    != 0)
** ***   * **      ****   * **** 
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* * ** *  *     * ** *  * ** 
 * ****** *  ** * *** ***    *  * count;
}

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 2

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

int main(void)
{
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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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}



int main(void)
{
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 ** *  **   * *  *  ****  ******   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);
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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)
{
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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)
 * ***   **  * *** ** *****  
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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 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)
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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'