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)
{
*  **** ***      * * ** *** *** * count=0;
*  *   *  *  **    **  * ***  *** != 0)
 *      ***   *  *   *** 
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   * **** **    **   **      ** ** ** * ** ** * *      /= 10;
     ***  * * **** **   ***
****  **    ***   *  **  ** ***   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 2

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

int main(void)
{
*    ** *  *  *     *  n;
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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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** *   ****  * *  
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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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    ****  * **    (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;
** ****      **** ** 
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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)
 *   **  ***     * *      
***    *   **  *  * *** * ** ******  ** ** *    *   *  *** ** *
 *   *  **    **  **   * *  **  * *      **  * ** **  **  /= 10;
***  *  **   **    **** *  
*  * *  ** **  *******  ***  * 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)
{
*****  *  *   ** *******  cnt=0;
  **  ** ** *** **********    **  != 0)
***** *   **** **  ** ** **  **
* *******     *  ** **   *    * *     *** * *  *****  * *  ** /= 10;
* *** ** * **** **   *** *  **  ** *** **  * *  ** *  ***
*  * *  ** * **   ***  
 *       *  *     ****  ** *   cnt;
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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)
{
  *** ** * **  *****  **  ** **   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)
{
 **** ** **  * * *    * * 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'