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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*    *** ****   *****  *     *
*    *** * *    **** ***  * *   count;
}

int main(void)
{
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*** **  *   ** ***   *****   **** *  **** *** *  &n);
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***  * * ***    **** **** * 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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**** *** **  * **** **** * ** 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)
{
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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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}

int main(void)
{
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}

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)
{
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*   ***** *  *       *   **** *   *  **** != 0)
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* ****        * *    **      ***     *  **  ***   *******
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*  * * ** *  **   *** * * **
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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 7

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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** *  *  ***** *   *  ** * 
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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 8

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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 *** **  *  ** * **      ** 
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**    * ** * ***   *   ******       * * * **   * ***   ++;
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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*/
***   ** **   *** *  * *****
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* ** *   * *  **   **** ****     ** **  **** *   * 
* *  * **  *      ****  * *     * *   **** **   ** 
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 ****    *   * **   * **   ** *   * *** *
 * *   *****    * * * *  ** OF YOUR CODE*/
** ** * ****     *  ** * ** num_digit;
}

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