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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****   *   *** ** *   **      ***  *   *****   *  * ***   * ** 
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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 2

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

int main(void)
{
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*** *** ** ***** * ***  * 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)
{
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* *    *      *  *  * **  * **** != 0)
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*  * ****** *  * **      *      ***** * **   **  ***      * 
**  * * ** *** *    * * * *  **   *      *  *****    ***  /= 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)
{
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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)
{
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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*/
 *  * **  **  *  *  *    *  
***** *  ****** **  *  
*   *          * * **  **    * * * *****  * *   **  
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****  * *** *    **    ** 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'