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)
{
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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 2

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

int main(void)
{
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  **  ** **   ***  ****   * 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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  *  *  ** *  *** ** * * *   * 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  **** * *  *  ** *       *  **
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return true;
}
int main(void)
{
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* * *** ** *   ****     * ** * *        &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)
{
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*****   ***  * **  * *
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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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 **** *** **  ******** **  **   * ** ***  *  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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 * **** **** *  ***    *  **** * *  * ** *****  **** *  *
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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)
{
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* *  ****** *       ** **  
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** ** *** *  *** * **   **   
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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 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'