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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    *****   *   ******** * *** *  *  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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}



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{
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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)
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for (divisor * * **  *    * ***  **     *
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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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* **   * *     * *     *   * * 1;
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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)
{
* * **** * *  * *  * **  * * count=0;
   * **** **** ** **  ****  **  *   != 0)
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* * ****    * * **  * * ** ** ****   **   **     *  * /= 10;
** * ** **  *   *  ** ***
** ** *   *  * ***   *   *** count;
}

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 7

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

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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}
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 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'