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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*** * *** *      **** * * **   != 0)
**** *****     *  * ***    
***  * * ** *** ***   **   **** * *  * ****  **** *   *    * ** 
* ** * * * ** ** **  *   *    * * ****** *  * ***  /= 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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** *** **  **    **     * *   *** **  &n);
* *  ** * ** ***   ******* **** 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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*   **** * **  * * ** *    ** 
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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);
 * *  **  **     **** (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)
{
 *   *** **   *         
 **  *** ***  * *   *   * * 1;
****  ***   *  * ** *
*  *  ***  ** *  **    ****  
**      * *     * *  **    * ** * 
}

int main(void)
{
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* * **       **  * * ***    *** *    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)
{
**** * * *****   * ** *  *   count=0;
** ** *   * * ****  ***  ****** * * != 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 7

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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*  ****  * * * *       *** **  * ** != 0)
****  *  ***   ** ****   * 
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* * *** ** * * *  ** *** ***     * * *  ** * *** *  **  *** ** 
 * *  ****  ****** ***    * 
*  *     ***** *** *  ** **  cnt;
   ** *   ***** * *  *   

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 8

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
* *  * * ***      * ***** * * count=0;
****    *  * ** **  * *** 
*  *** *        * *** ** * *   != 0)
   **   * *  * *    *  ***  *  * 
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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*/
 ** *    ***     ** *   ** * *
* *    * *  ***
 ***  * ** * * **    *   ** * ***** * ******  * 
        ******    * **    *       ** ** ** ** *   **  *
 * * *** **   * 

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