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)
*** ***    ****   * **    ****
*  **  ***  **  * **   * **** *** * ** ** *****   * * * *  *
****  * **** ****  ** *   **  **  * * *  *  *** * * *  *  * /= 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)
{
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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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****  *** **    *  ***    *** * **   &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)
{
*  ***   * *   ****  *  n;
  *  *  * ** *** **  ***  *** *  ** *** &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;
 ***  * *****    ** *
 * *  *  * *    *     * 
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}

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