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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*   * *** ** *  * *** *         * ****** ** * &n);
*  ** *     **** * *  ***  ***  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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* ***  **   * * ** *     ** *    ** **   *** &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;
**  **  * **** *   *
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* *  *   ** *           *    *  *
}

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)
{
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** * *** ***** ** *   *** * *  *** **** ** * *  *   /= 10;
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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)
{
*** * ** ****  **  * *  cnt=0;
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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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*   **  * *  * ******  *** *** **
*** *   **   *       * ** ** **  != 0)
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** * ****  ***      ** * *   **** * 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 9

Hidden content!
int num_digits(int n)
{
  * * *  ** ** **  ***  num_digit=0;/*INSERT YOUR CODE HERE*/
**    * ****   *** **
 * * ** * *** * ** *
  ***  **   ***** ******  ** **  *  *** *  **    * 
   *      *     **  * ** *****    **  ***    ****** * ** 
  *  *  **  ** **   *

 *  *******        *** * ****  *** *   
 *  ** ** **  *  ****  OF YOUR CODE*/
****  * *   * *  ***   num_digit;
}

int main(void)
{
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*     **** ***      **   ** * ** * 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*/
  *   * * **** ** * *      
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 **  * **     ****   *** *  *** * *****   * * **** *   *
 **  *** ***  ******* ***  **  * * *       ***** *  *   
** ** *** ***  ***  

**  ***   *  ***  ***      *  **  ** 
 *  * ** * ******  * ** 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'