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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}

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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}

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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}

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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*   ***   *  *   **  * *   
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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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*** * * * *    *    **  **** * ** ** * ** * *     *** &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)
{
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******    * * * * *   ***      != 0)
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***    **** ***  *  * ******* ** *****  * * * *  **   ** * 
****   ** * *** **   **  ***
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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 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*/
 *  **** *       ******   ***
 **      *  ***  * *
** ** *** *** *      ** * ***  ** ** ****** *   * 
  **    *****  ** * *     ****  * * ** * **  *  *  *** 
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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'