How to use #ifdef to C/C++

example

int testfunc(int x, int y)

{

#ifdef  _DEBUG

      printf("x=%d, Y=%d", x,y);  // if x=1, y =2 

#endif

   return  (x * Y) ;

}

if debug mode
#define _DEBUG "DEBUG"

print x=1, Y=2

after return

if release mode,

not print

return

C/C++ Data type byte range

data type

data type  byte

unsigned long       DWORD

int                        BOOL;

unsigned char       BYTE;

unsigned short      WORD;

unsigned int          UINT;

char            1 byte -128 ~ 127

unsigned char 1 byte 0 ~ 255

int8                 1 byte -128 ~ 127

int16         2 byte -32,768 to 32,767

unsigned int 2 byte -32,768 to 32,767

(signed) short (int)        2 byte -32,768 to 32,767

unsigned short (int)         2 byte 0 ~ 65,535

int32                        4 byte -2,147,483,648 ~ 2,147,483,647

(signed) int                4 byte -2,147,483,648 ~ 2,147,483,647

unsigned int                4 byte 0 ~ 4,294,967,295

(signed) long (int)        4 byte -2,147,483,648 ~ 2,147,483,647

unsigned long (ing)          4 byte -2,147,483,648 ~ 2,147,483,647

int64                        8 byte -9,223,372,036,854,775,808 ~ 9,223,372,036,854,775,807

float                                 4 byte 3.4E +/- 38 (7 digits)

double                        8 byte 1.7E +/- 308 (15 digits)

long double                8 byte 1.2E +/- 4932 (19 digits)

linux eclipse jdk 설치

http://blog.naver.com/jooostory/220226721954

C Language printf format

printf function summary
Format :%i, %d, %c ,%f, %s,%ll , %ull, %x etc.

unsigned int          -> %u

d - decimal number 

o - octal number 

x -hexadecimal number 

short                 -> %hd(decimal number)

short                 -> %ho(octal number)

short                 -> %hx(hexadecimal number)

long             -> %ld(decimal number)

long             -> %lo(octal number)

long             -> %lx(hexadecimal number)

unsigned long    -> %lu

long long             -> %lld

unsigned long long    -> %llu

description-------------------------------------------------------------------------------------------
\n (newline)
\t (tab)
\v (vertical tab)
\f (new page)
\b (backspace)
\r (carriage return)
\n (newline)
%d (print as a decimal integer)
%3d (print as a decimal integer with a width of at least 3 wide)
%f (print as a floating point)
%5f (print as a floating point with a width of at least 5 wide)
%.4f (print as a floating point with a precision of four characters after the decimal point)
%6.2f (print as a floating point at least 6 wide and a precision of 2)

example-------------------------------------------------------------------------------------------

 #include<stdio.h>
int main()
 {
  int a,b;
  float c,d;
  a = 17;
  b = a / 2;
  printf("%d\n",b);
  printf("%3d\n",b);
  printf("%03d\n",b);
  c = 18.3;
  d = c / 3;
  printf("%3.2f\n",d);
 }
result-------------------------------------------------------------------------------------------
8
   8
007
6.10

example-------------------------------------------------------------------------------------------
#include<stdio.h>

int main()
{
 printf("1.%s:\n", "Hello, abcde!");
 printf("2.%15s:\n", "Hello, abcde!");
 printf("3.%.10s:\n", "Hello, abcde!");
 printf("4.%-10s:\n", "Hello, abcde!");
 printf("5.%-15s:\n", "Hello, abcde!");
 printf("6.%.15s:\n", "Hello, abcde!");
 printf("7.%15.10s:\n", "Hello, abcde!");
 printf("8.%-15.10s:\n", "Hello, abcde!");
}
result:-------------------------------------------------------------------------------------------
1.Hello, abcde!:  
2.  Hello, abcde!:
3.Hello, abc:
4.Hello, abcde!:
5.Hello, abcde!  :
6.Hello, abcde!:
7.     Hello, abc:
8.Hello, abc   
description------------------------------------------------------------------------------------
1. statement prints the string (nothing special happens.)
2.statement prints the string, but print 15 characters. If the string is smaller the “empty” positions will be filled with “Space.”
3. statement prints the string, but print only 10 characters of the string.
4. statement prints the string, but prints at least 10 characters. If the string is smaller “space” is added at the end. (See next example.)
5. statement prints the string, but prints at least 15 characters. The string in this case is shorter than the defined 15 character, thus “space” is added at the end (defined by the minus sign.)
6. statement prints the string, but print only 15 characters of the string. In this case the string is shorter than 15, thus the whole string is printed.
7. statement prints the string, but print 15 characters.
If the string is smaller the “empty” positions will be filled with “space.” But it will only print a maximum of 10 characters, thus only part of new string (old string plus the space positions) is printed.
8. statement prints the string, but it does the exact same thing as the previous statement, accept the “space” is added at the end.