c ++ learning record (a)

c ++ learning basic learning record (a)

c ++ language is the expansion and improvement of object-oriented programming language based on the C language. So mostly c ++ basics similar to the C language, learning the C language, the foundation can quickly spend learning c ++ language.

1.c ++ data types, modifiers, variables and constants

(1) Data Types

c ++ data types are basic built-in types, typedef statement, enumerated types, etc.

· Basic built-in types

Types of	Keyword
Boolean	bool
Character	char
Integer	int
Float	float
Dual Float	double
Untyped	void
Wide character	wchar_t

· Typedef statement

typedef may take a new name for an existing type. Such as

\\typedef int abc;
  abc h=1;

· Enumerated type

\\enum 枚举名{x,x,x,x}枚举变量；

c ++ base data type in C language is the same, except wchar_t, character constants are enclosed in single quotes. If the constants L (only when capitalized) beginning indicates that it is a wide character constants (e.g. L'x '), at which time it must be stored in a variable of type wchar_t. Otherwise, it is a narrow character constants (e.g., 'x'), where it can be stored in simple variable of type char. .

(2) Modifiers

char, int, double base type may be used signed, unsigned, short, long modified modifier. Wherein the modifier is signed, unsigned, long, short modification int; signed, unsigned char modification; Long modified double.

(3) constant and variable

c ++ as in the definition of methods and definitions of constants and variables. There are also global variables and local variables

2.c ++ basic input and output, and comments

c ++ header files Standard defines a job input stream cin, cout standard output stream, cerr unbuffered clog standard error and standard error stream buffer.

cost

flow cout << insert used in conjunction operator, output variables, << be used multiple times in a statement, such as:

\\cout << "hello world"<< endl; #endl表示换行

China

cin and extracting operator >> combination, extracting operator >> can be used repeatedly in a statement

Palau

cerr is non-buffered and immediately outputs

clog

clog is buffered, only the buffer fills or output buffer will refresh

Note

c ++ // comment line to order / and / multi-line comments.

3.c ++ references

c ++ pointer referenced similarly. However, there are three different references:

· Null reference does not exist. Reference must be connected to a legitimate memory.

· Once the reference is initialized to an object, it can not be directed to another object.

· Reference must be initialized when created.

It is a symbol reference & usage similar to the following:

\\int i；
  int& r=i;

4. arrays, loops, is determined, the operator language are the same C

Summary: basic knowledge of c ++ and C language is almost the same, the biggest difference is probably the C language is a process-oriented language and c ++ is an object-oriented language, go to the back of the learning experience can make a difference.