TXT

CReferenceCard1

By Sylvia Perez,2014-04-13 03:04
7 views 0
CReferenceCard1

     本文由foxmouse521贡献

     pdf文档可能在WAP端浏览体验不佳。建议您优先选择TXT?或下载源文件到本机查看。

     C++ Reference Card

     Key

     switch keyword, reserved “Hello!” – string // comment commented code

    close() library function main variable, identifier variable placeholder in

    syntax if (exression) - syntax statement;

     2002 Greg Book Control Structures

     Decision (if-else) if (condition) { statements; } else if (condition) { statements; } else { statements; } if (x == 3) // curly braces not needed flag = 1; // when if statement is else // followed by only one flag = 0; // statement Repetition (while) while (expression) { // loop until statements; // expression is false } Repetition (do-while) do { // perform the statements statements; // as long as condition } while (condition); // is true Repetition (for) init - initial value for loop control variable condition - stay in the loop as long as condition is true increment - change the loop control variable for(init; condition; increment) { statements; } Bifurcation (break, continue, goto, exit) break; // ends a loop continue; // stops executing statements // in current iteration of loop cont// inues executing on next iteration label: goto label; // execution continues at // label exit(retcode); // exits program Selection (switch) switch (variable) { case constant1: // chars, ints statements; break; // needed to end flow case constant2: statements; break; default: statements; // default statements }

     C++ Program Structure

     // my first program in C++ #include int main () { cout << “Hello World!”; return

    0; } // single line comment /* multi-line comment */

     Functions

     In C, functions must be prototyped before the main function, and defined after the main function. In C++, functions may, but do not need to be, prototyped. C++ functions must be defined before the location where they are called from. // function declaration type name(arg1, arg2, „„) { statement1; statement2; „„ } type –

    return type of the function name name by which the function is called arg1, arg2

     parameters to the function statement statements inside the function // example

    function declaration // return type int int add(int a, int b) { // parms int r; // declaration r = a + b; // add nums return r; // return value } // function call num = add(1,2); Passing Parameters Pass by Value function(int var); // passed by value Variable is passed into the function and can be changed, but changes are not passed back. Pass by Constant Value function(const int var); Variable is passed into the function but cannot be changed. Pass by Reference function(int &var); // pass by reference Variable is passed into the function and can be changed, changes are passed back. Pass by Constant Reference function(const int &var); Variable cannot be changed in the function. Passing an Array by Reference It’s a waste of memory to pass arrays

    and structures by value, instead pass by reference. int array[1]; // array declaration ret = aryfunc(&array); // function call int aryfunc(int *array[1]) { array[0] = 2; // function return 2; // declaration } Default Parameter Values int add(int a, int

    b=2) { int r; r=a+b; // b is always 2 return (r); } Overloading Functions Functions can have the same name, and same number of parameters as long as the parameters of are different types // takes and returns integers int divide (int a, int b) { return (a/b); } // takes and returns floats float divide (float a, float b) { return (a/b); } divide(10,2); // returns 5 divide(10,3); // returns 3.33333333 Recursion Functions can call themselves long factorial (long n) { if (n > 1) return (n * factorial (n-1)); else return (1); } Prototyping Functions can be prototyped so they can be used after being declared in any order // prototyped functions can be used // anywhere in the program #include void odd (int a); void even (int a); int main () { „„ }

     Identifiers

     These are ANSI C++ reserved words and cannot be used as variable names. asm, auto, bool, break, case, catch, char, class, const, const_cast, continue, default, delete, do, double, dynamic_cast, else, enum, explicit, extern, false, float, for, friend, goto, if, inline, int, long, mutable, namespace, new, operator, private, protected, public, register, reinterpret_cast, return, short, signed, sizeof, static, static_cast, struct, switch, template, this, throw, true, try, typedef, typeid, typename, union, unsigned, using, virtual, void, volatile, wchar_t

     Data Types

     Variable Declaration special class size sign type name; special: volatile class: register, static, extern, auto size: long, short, double sign: signed, unsigned type: int, float, char (required) name: the variable name (required) // example of variable declaration extern short unsigned char AFlag; TYPE SIZE RANGE char 1 signed -128 to 127 unsigned 0 to 255 short 2 signed -32,768 to 32,767 unsigned 0 to 65,535 long 4 signed -2,147,483,648 to 2,147,483,647 unsigned 0 - 4,294,967,295 int varies depending on system float 4 3.4E +/- 38 (7 digits) double 8 1.7E +/- 308 (15 digits) long double 10 1.2E +/- 4,932 (19 digits) bool 1 true or false wchar_t 2 wide characters Pointers type *variable; // pointer to variable type *func(); // function returns pointer void * // generic pointer type NULL; // null pointer *ptr; // object pointed to by pointer &obj // address of object Arrays int arry[n]; // array of size n int arry2d[n][m]; // 2d n x m array int arry3d[i][j][k]; // 3d i x j x k array Structures struct name { type1 element1; type2 element2; „„ } object_name ; // instance of name name variable; // variable of type name variable.element1; // ref. of element variable->element1; // reference of pointed to structure 1 2

     Operators

     priority/operator/desc/ASSOCIATIVITY :: scope LEFT () parenthesis LEFT [ ] brackets LEFT -> pointer reference LEFT . structure member access LEFT sizeof returns memory size LEFT ++ increment RIGHT decrement RIGHT ~ complement to one (bitwise)

    RIGHT ! unary NOT RIGHT & reference (pointers) RIGHT * dereference RIGHT (type) type casting RIGHT + - unary less sign RIGHT * multiply LEFT / divide LEFT % modulus LEFT + addition LEFT - subtraction LEFT << bitwise shift left LEFT >> bitwise shift right LEFT < less than LEFT <= less than or equal LEFT > greater than LEFT >= greater than or equal LEFT == equal LEFT != not equal LEFT & bitwise AND LEFT ^ bitwise NOT LEFT | bitwise OR LEFT && logical AND LEFT || logical OR LEFT ? : conditional RIGHT = assignment += add/assign -= subtract/assign *= multiply/assign /= divide/assign %=

    modulus/assign >>= bitwise shift right/assign <<= bitwise shift left/assign &= bitwise AND/assign ^= bitwise NOT/assign |= bitwise OR/assign , comma

     3

     4

     5 6 7

     Console Input/Output

     [See File I/O on reverse for more about streams] C Style Console I/O stdin

    standard input stream stdout standard output stream stderr standard error stream

    // print to screen with formatting printf(“format”, arg1,arg2,„„);

    printf(“nums: %d, %f, %c”, 1,5.6,’C’); // print to string s sprintf(s,”format”,

    arg1, arg2,„„); sprintf(s,”This is string # %i”,2); // read data from keyboard

    into // name1,name2,„„ scanf(“format”,&name1,&name2, „„);

    scanf(“%d,%f”,var1,var2); // read nums // read from string s

    sscanf(“format”,&name1,&name2, „„); sscanf(s,“%i,%c”,var1,var2); C Style I/O Formatting %d, %i integer %c single character %f double (float) %o octal %p pointer %u unsigned %s char string %e, %E exponential %x, %X hexadecimal %n number of chars written %g, %G same as f for e,E C++ console I/O cout<< console out, printing to screen cin>> console in, reading from keyboard cerr<< console error clog<< console log cout<<“Please enter an integer: ”; cin>>i; cout<<“num1: ”pApple->price = 0.35; // assignment

     User Defined DataTypes

     typedef existingtype newtypename ; typedef unsigned int WORD; enum name{val1, val2, „„} obj_name; enum days_t {MON,WED,FRI} days; union model_name { type1 element1; type2 element2; „„ } object_name ; union mytypes_t { char c; int i; } mytypes; struct packed { // bit fields unsigned int flagA:1; // flagA is 1 bit unsigned int flagB:3; // flagB is 3 bit }

     Namespaces

     Namespaces allow global identifiers under a name // simple namespace namespace identifier { namespace-body; } // example namespace namespace first {int var = 5;} namespace second {double var = 3.1416;} int main () { cout << first::var << endl; cout << second::var << endl; return 0; } using namespace allows for the current nesting level to use the appropriate namespace using namespace identifier; // example using namespace namespace first {int var = 5;} namespace second {double var = 3.1416;} int main () { using namespace second; cout << var << endl; cout << (var*2) << endl; return 0; }

     Preprocessor Directives

     #define ID value // replaces ID with //value for each occurrence in the code #undef ID // reverse of #define #ifdef ID //executes code if ID defined #ifndef ID // opposite of #ifdef #if expr // executes if expr is true #else // else #elif // else if #endif // ends if block #line number “filename” // #line controls what line number and // filename appear when a compiler error // occurs #error msg //reports msg on cmpl. error #include “file” // inserts file into code // during compilation #pragma //passes parameters to compiler

     Character Strings

     The string “Hello” is actually composed of 6 characters and is stored in memory

    as follows: Char H e l l o \0 Index 0 1 2 3 4 5 \0 (backslash zero) is the null terminator character and determines the end of the string. A string is an array of characters. Arrays in C and C++ start at zero. str = “Hello”; str[2] = ‘e’; // string is now ‘Heelo’ common functions: strcat(s1,s2) strchr(s1,c) strcmp(s1,s2) strcpy(s2,s1) strlen(s1) strncpy(s2,s1,n) strstr(s1,s2)

     Exceptions

     try { // code to be tried„„ if statements statements; // fail, exception is set throw exception; } catch (type exception) { // code in case of exception statements; }

     Class Reference

     Class Syntax class classname { public: classname(parms); // constructor ~classname(); // destructor member1; member2; protected: member3; „„ private: member4; } objectname; // constructor (initializes variables)

    classname::classname(parms) { } // destructor (deletes variables)

    classname::~classname() { } public members are accessible from anywhere where the class is visible protected members are only accessible from members of the same class or of a friend class private members are accessible from members of the same class, members of the derived classes and a friend class constructors may be overloaded just like any other function. define two identical constructors with difference parameter lists Class Example class CSquare { // class declaration public: void Init(float h, float w); float GetArea(); // functions private: // available only to CSquare float h,w; } // implementations of functions void CSquare::Init(float hi, float wi){ h = hi; w = wi; } float CSquare::GetArea() { return (h*w); } // example declaration and usage CSquare theSquare; theSquare.Init(8,5); area = theSquare.GetArea(); // or using a pointer to the class CSquare *theSquare; theSquare->Init(8,5); area = theSquare->GetArea();

     File I/O

     #include // read/write file #include // write file #include // read file File I/O is done from the fstream, ofstream, and ifstream classes. File Handles A file must have a file handle (pointer to the file) to access the file. ifstream infile; // create handle called // infile to read from a file ofstream outfile; // handle for writing fstream f; // handle for read/write Opening Files After declaring a file handle, the following syntax can be used to open the file void open(const char *fname, ios::mode); fname should be a string, specifying an absolute or relative path, including filename. ios:: mode can be any number of the following and repeat: in Open file for reading out Open file for writing ate Initial position: end of file app Every output is appended at the end of file trunc If the file already existed it is erased binary Binary mode ifstream f; // open input file example f.open(“input.txt”, ios::in); ofstream f; // open for writing in

    binary f.open(“out.txt”, ios::out | ios::binary | ios::app); Closing a File A file can be closed by calling the handle’s close function f.close(); Writing To a File (Text Mode) The operator << can be used to write to a file. Like cout, a stream can be opened to a device. For file writing, the device is not the console, it is the

    file. cout is replaced with the file handle. ofstream f; // create file handle f.open(“output.txt”) // open file f <<“Hello World\n”<> can be used to read from

    a file. It works similar to cin. Fields are seperated in the file by spaces. ifstream f; // create file handle f.open(“input.txt”); // open file while (!f.eof()) // end of file test f >>a>>b>>c; // read into a,b,c I/O State Flags Flags are set if errors or other conditions occur. The following functions are members of the file object handle.bad() returns true if a failure occurs in reading or writing handle .fail() returns true for same cases as bad() plus if formatting errors occur handle.eof() returns true if the end of the file reached when reading handle.good() returns false if any of the above were true Stream Pointers handle.tellg() returns pointer to current location when reading a file handle.tellp() returns pointer to current location when writing a file // seek a position in reading a file

    handle.seekg(position); handle.seekg(offset, direction); // seek a position in writing a file handle.seekp(position); handle.seekp(offset, direction); direction can be one of the following ios::beg beginning of the stream ios::cur current position of the stream pointer ios::end end of the stream Binary Files buffer is a location to store the characters. numbytes is the number of bytes to written or read. write(char *buffer, numbytes); read(char *buffer, numbytes); Output Formatting streamclass f; // declare file handle // set output flags f.flags(ios_base::flag ) possible flag s dec fixed hex oct scientific internal left right uppercase boolalpha showbase showpoint showpos skipws unitbuf adjustfield left | right | internal basefield dec | oct | hex floatfield scientific | fixed f.fill() get fill character f.fill(c h) set fill character ch f.precision( numdigits) sets the precision for floating point numbers to numdigits f.put( c ) put a single char into output stream f.setf(flag) sets a flag f.setf(flag, mask) sets a flag w/value f.width() returns the current number of characters to be written f.width(num) sets the number of chars to be written

     ACSII Chart

     Dec 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 C har N UL SO H ST X ET X EO T ENQ ACK BEL BS T AB LF VT B FF CR SO SI D LE D C1 D C2 D C3 D C4 N AK SYN ET B C AN EM SUB ESC FS GS RS US ! “ #

    $ % & ‘ ( ) * + , . / 0 1 2 3 4 5 6 7 8 9 : ; < = > ? Dec 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 Char @ A B C D E F G H I J K L M N O P Q R S T U V W X Y Z [ \ ] ^ _ ` a b c d e f g h i j k l m n o p q r s t u v w x y z { | } ~ ? Dec 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 Char ì ã à ä â å ç ê ? á æ è ë ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? Dec 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 Char ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?

? ? ? ? ? ? ? α Γ π Σ ζ η Φ Θ δ ? θ ε ? ? ? ? ? ? ? é ? ? ?

    ? ?

     Inheritance

     Functions from a class can be inherited and reused in other classes. Multiple inheritance is possible. class CPoly { //create base polygon class protected: int width, height; public: void SetValues(int a, int b) { width=a; height=b;} }; class COutput { // create base output public: // class void Output(int i); }; void COutput::Output (int i) { cout << i << endl; } // CRect inherits SetValues from Cpoly // and inherits Output from COutput class CRect: public CPoly, public COutput { public: int area(void) { return (width * height); } }; // CTri inherits SetValues from CPoly class CTri: public CPoly { public: int area(void) { return (width * height / 2); } }; void main () { CRect rect; // declare objects CTri tri; rect.SetValues (2,9); tri.SetValues (2,9); rect.Output(rect.area()); cout<

     Templates

     Templates allow functions and classes to be reused without overloading them template function; template function; // function example template T GetMax (T a, T b) { return (a>b?a:b); // return the larger } void main () { int a=9, b=2, c; float x=5.3, y=3.2, z; c=GetMax(a,b); z=GetMax(x,y); } // class example template class CPair { T x,y; public: Pair(T a, T b){ x=a; y=b; } T GetMax(); }; template T Pair::GetMax() { // implementation of GetMax function T ret; // return a template ret = x>y?x:y; // return larger return ret; } int main () { Pair theMax (80, 45); cout << theMax.GetMax(); return 0; }

     Overloading Operators

     Like functions, operators can be overloaded. Imagine you have a class that defines a square and you create two instances of the class. You can add the two objects together. class CSquare { // declare a class public: // functions void Init(float h, float w); float GetArea(); CSquare operator + (CSquare); private: // overload the ‘+’ operator float h,w; } // function implementations void CSquare::Init(float hi, float wi){ h = hi; w = wi; } float CSquare::GetArea() { return (h*w); }// implementation of overloaded operator CSquare CSquare::operator+ (CSquare cs) { CSquare temp; // create CSquare object temp.h = h + cs.h; // add h and w to temp.w = w + cs.w; // temp object return (temp); } // object declaration and usage CSquare sqr1, sqr2, sqr3; sqr1.Init(3,4); // initialize objects sqr2.Init(2,3); sqr3 = sqr1 + sqr2; // object sqr3 is now (5,7)

     Dynamic Memory

     Memory can be allocated and deallocated // allocate memory (C++ only) pointer = new type []; int *ptr; // declare a pointer ptr = new int; // create a new instance ptr = new int [5]; // new array of ints // deallocate memory (C++ only) delete [] pointer; delete ptr; // delete a single int delete [] ptr // delete array // allocate memory (C or C++) void * malloc (nbytes); // nbytes=size char *buffer; // declare a buffer // allocate 10 bytes to the buffer buffer = (char *)malloc(10); // allocate memory (C or C++) // nelements = number elements // size = size of each element void * malloc (nelements, size); int *nums; // declare a buffer // allocate 5 sets of ints nums = (char *)calloc(5,sizeof(int)); // reallocate memory (C or C++) void * realloc

(*ptr, size); // delete memory (C or C++) void free (*ptr);

     Friend Classes/Functions

     Friend Class Example class CSquare; // define CSquare class CRectangle { int width, height; public: void convert (CSquare a); }; class CSquare { // we want to use the private: // convert function in int side; // the CSquare class, so public: // use the friend keyword void set_side (int a) { side=a; } friend class CRectangle; }; void CRectangle::convert (CSquare a) { width = a.side; height = a.side; } // declaration and usage CSquare sqr; CRectangle rect; // convert can be sqr.set_side(4); // used by the rect.convert(sqr); // rectangle class Friend Functions A friend function has the keyword friend in front of it. If it is declared inside a class, that function can be called without reference from an object. An object may be passed to it. /* change can be used anywhere and can have a CRect object passed in */ // this example defined inside a class friend CRect change(CRect); CRectangle recta, rectb; // declaration rectb = change(recta); // usage

     Advanced Class Syntax

     Static Keyword static variables are the same throughout all instances of a class. static int n; // declaration CDummy::n; // reference Virtual Members Classes may have virtual members. If the function is redefined in an inherited class, the parent must have the word virtual in front of the function definition This keyword The this keyword refers to the memory location of the current object. int func(this); // passes pointer to // current object Class TypeCasting reinterpret_cast dynamic_cast static_cast const_cast

     ANSI C++ Library Files

     The following files are part of the ANSI C++ standard and should work in most compilers.

    

     (expression); (expression); (expression); (expression);

     Expression Type The type of an expression can be found using typeid. typeid returns a type. typeid(expression);

     C++ Reference Card

     C/C++ Syntax, DataTypes, Functions Classes, I/O Stream Library Functions

     2002 The Book Company Storrs, CT refcard@gbook.org

     Information contained on this card carries no warranty. No liability is assumed by the maker of this card for accidents or damage resulting from its use.

1

Report this document

For any questions or suggestions please email
cust-service@docsford.com