बुधवार, 12 अक्तूबर 2011

C++ QUICK REFERENCE


C++ QUICK REFERENCE













PREPROCESSOR
// Comment to end of line
/* Multi-line comment */
#include // Insert standard header file
#include "myfile.h" // Insert file in current directory
#define X some text // Replace X with some text
#define F(a,b) a+b // Replace F(1,2) with 1+2
#define X \
some text // Line continuation
#undef X // Remove definition
#if defined(X) // Condional compilation (#ifdef X)
#else // Optional (#ifndef X or #if !defined(X))
#endif // Required after #if, #ifdef
LITERALS
255, 0377, 0xff // Integers (decimal, octal, hex)
2147483647L, 0x7fffffffl // Long (32-bit) integers
123.0, 1.23e2 // double (real) numbers
'a', '\141', '\x61' // Character (literal, octal, hex)
'\n', '\\', '\'', '\"' // Newline, backslash, single quote, double
quote
"string\n" // Array of characters ending with newline and
\0
"hello" "world" // Concatenated strings
true, false // bool constants 1 and 0
DECLARATIONS
int x; // Declare x to be an integer (value undefined)
int x=255; // Declare and initialize x to 255
short s; long l; // Usually 16 or 32 bit integer (int may be
either)
char c='a'; // Usually 8 bit character
unsigned char u=255; signed char s=-1; // char might be either
unsigned long x=0xffffffffL; // short, int, long are signed
float f; double d; // Single or double precision real (never
unsigned)
bool b=true; // true or false, may also use int (1 or 0)
int a, b, c; // Multiple declarations
int a[10]; // Array of 10 ints (a[0] through a[9])
int a[]={0,1,2}; // Initialized array (or a[3]={0,1,2}; )
int a[2][3]={{1,2,3},{4,5,6}}; // Array of array of ints
char s[]="hello"; // String (6 elements including '\0')
int* p; // p is a pointer to (address of) int
char* s="hello"; // s points to unnamed array containing "hello"
void* p=NULL; // Address of untyped memory (NULL is 0)
int& r=x; // r is a reference to (alias of) int x
enum weekend {SAT,SUN}; // weekend is a type with values SAT and SUN
enum weekend day; // day is a variable of type weekend
enum weekend {SAT=0,SUN=1}; // Explicit representation as int
enum {SAT,SUN} day; // Anonymous enum
typedef String char*; // String s; means char* s;
const int c=3; // Constants must be initialized, cannot assign
to
const int* p=a; // Contents of p (elements of a) are constant
int* const p=a; // p (but not contents) are constant
const int* const p=a; // Both p and its contents are constant
const int& cr=x; // cr cannot be assigned to change x
STORAGE CLASSES
int x; // Auto (memory exists only while in scope)
static int x; // Global lifetime even if local scope
extern int x; // Information only, declared elsewhere
STATEMENTS
x=y; // Every expression is a statement
int x; // Declarations are statements
; // Empty statement
{ // A block is a single statement
int x; // Scope of x is from declaration to end of
block
a; // In C, declarations must precede statements
}
if (x) a; // If x is true (not 0), evaluate a
else if (y) b; // If not x and y (optional, may be repeated)
else c; // If not x and not y (optional)
while (x) a; // Repeat 0 or more times while x is true
for (x; y; z) a; // Equivalent to: x; while(y) {a; z;}
do a; while (x); // Equivalent to: a; while(x) a;
switch (x) { // x must be int
case X1: a; // If x == X1 (must be a const), jump here
case X2: b; // Else if x == X2, jump here
default: c; // Else jump here (optional)
}
break; // Jump out of while, do, or for loop, or switch
continue; // Jump to bottom of while, do, or for loop
return x; // Return x from function to caller
try { a; }
catch (T t) { b; } // If a throws a T, then jump here
catch (...) { c; } // If a throws something else, jump here
FUNCTIONS
int f(int x, int); // f is a function taking 2 ints and returning
int
void f(); // f is a procedure taking no arguments
void f(int a=0); // f() is equivalent to f(0)
f(); // Default return type is int
inline f(); // Optimize for speed
f() { statements; } // Function definition (must be global)
T operator+(T x, T y); // a+b (if type T) calls operator+(a, b)
T operator-(T x); // -a calls function operator-(a)
T operator++(int); // postfix ++ or -- (parameter ignored)
extern "C" {void f();} // f() was compiled in C

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