C++编程语言教程 - cplusplus.com 官方文档概述

需积分: 34 20 浏览量更新于2024-07-29 收藏 1.21MB PDF 举报

"C++官方文档，主要来源于c++．com，由Juan Soulié编写，最后一次修订于2007年6月。该文档提供在线版本，并不断更新，可能包含修正和变动。此文档及其内容受c++．com的版权保护，未经允许，禁止任何形式的再分布或复制，个人可以打印整份文档或将之下载到本地硬盘，但不得修改内容，包括版权信息。未经c++．com的书面许可，不得分发文档内容，也不得在任何其他网站或电子检索系统中存储或传输。" C++是一种强大的、通用的编程语言，它的设计结合了过程化编程、面向对象编程和泛型编程的特点。C++官方文档是学习和掌握该语言的重要参考资料。文档通常包括语言教程、标准库参考、编程指南等多个部分，旨在帮助开发者理解和应用C++的各种特性。文档的"Table of contents"（目录）部分是了解整个文档结构的关键，它列出了所有主题和子主题，使得用户能够快速定位到他们感兴趣的内容。例如，"Introduction"（介绍）部分通常会概述C++语言的基本概念，"Instructions for use"（使用指南）则可能会指导读者如何有效地使用这份文档，包括查找信息、理解示例代码等。 C++语言教程可能涵盖以下知识点： 1. **基本语法**：包括变量声明、数据类型、运算符、流程控制语句（如if、switch、for、while）等。 2. **函数**：函数定义、参数传递、函数指针等。 3. **类与对象**：面向对象编程的基础，包括类的定义、对象的创建、封装、继承、多态等。 4. **模板**：泛型编程的核心，用于创建可应用于不同数据类型的函数和类。 5. **异常处理**：错误处理机制，如何抛出和捕获异常。 6. **内存管理**：动态内存分配（new和delete）、栈与堆的区别。 7. **预处理器**：宏定义、条件编译等。 8. **标准库**：包括STL（标准模板库），如容器（vector、list、map等）、算法、迭代器、输入/输出流等。这些知识点的深入学习需要结合实际编程实践，通过编写和调试代码来巩固理解。同时，官方文档通常会提供丰富的示例代码和解释，以帮助读者更好地理解和应用C++的特性。在学习过程中，遵循文档中的指引，逐步学习和掌握每个概念，是提高编程技能的有效方法。

A first difference with fundamental data types is that in order to declare and use objects (variables) of this type we

need to include an additional header file in our source code: <string> and have access to the std namespace

(which we already had in all our previous programs thanks to the using namespace statement).

// my first string

#include <iostream>

#include <string>

using namespace std;

int main ()

{

string mystring = "This is a string";

cout << mystring;

return 0;

}

This is a string

As you may see in the previous example, strings can be initialized with any valid string literal just like numerical

type variables can be initialized to any valid numerical literal. Both initialization formats are valid with strings:

string mystring = "This is a string";

string mystring ("This is a string");

Strings can also perform all the other basic operations that fundamental data types can, like being declared without

an initial value and being assigned values during execution:

// my first string

#include <iostream>

#include <string>

using namespace std;

int main ()

{

string mystring;

mystring = "This is the initial string content";

cout << mystring << endl;

mystring = "This is a different string content";

cout << mystring << endl;

return 0;

}

This is the initial string content

This is a different string content

For more details on C++ strings, you can have a look at the string class reference.

Constants

Constants are expressions with a fixed value.

Literals

Literals are used to express particular values within the source code of a program. We have already used these

previously to give concrete values to variables or to express messages we wanted our programs to print out, for

example, when we wrote:

a = 5;

the 5 in this piece of code was a literal constant.

Literal constants can be divided in Integer Numerals, Floating-Point Numerals, Characters, Strings and Boolean

Values.

Integer Numerals

1776

707

-273

They are numerical constants that identify integer decimal values. Notice that to express a numerical constant we

do not have to write quotes (") nor any special character. There is no doubt that it is a constant: whenever we

write 1776 in a program, we will be referring to the value 1776.

In addition to decimal numbers (those that all of us are used to use every day) C++ allows the use as literal

constants of octal numbers (base 8) and hexadecimal numbers (base 16). If we want to express an octal number

we have to precede it with a 0 (zero character). And in order to express a hexadecimal number we have to precede

it with the characters 0x (zero, x). For example, the following literal constants are all equivalent to each other:

75 // decimal

0113 // octal

0x4b

// hexadecimal

All of these represent the same number: 75 (seventy-five) expressed as a base-10 numeral, octal numeral and

hexadecimal numeral, respectively.

Literal constants, like variables, are considered to have a specific data type. By default, integer literals are of type

int. However, we can force them to either be unsigned by appending the u character to it, or long by appending l:

75 // int

75u // unsigned int

75l // long

75ul

// unsigned long

In both cases, the suffix can be specified using either upper or lowercase letters.

Floating Point Numbers

They express numbers with decimals and/or exponents. They can include either a decimal point, an e character

(that expresses "by ten at the Xth height", where X is an integer value that follows the e character), or both a

decimal point and an e character:

3.14159 // 3.14159

6.02e23 // 6.02 x 10^23

1.6e-19 // 1.6 x 10^-19

3.0 // 3.0

These are four valid numbers with decimals expressed in C++. The first number is PI, the second one is the

number of Avogadro, the third is the electric charge of an electron (an extremely small number) -all of them

approximated- and the last one is the number three expressed as a floating-point numeric literal.

The default type for floating point literals is double. If you explicitly want to express a float or long double

numerical literal, you can use the f or l suffixes respectively:

3.14159L // long double

6.02e23f // float

Any of the letters that can be part of a floating-point numerical constant (e, f, l) can be written using either lower

or uppercase letters without any difference in their meanings.

Character and string literals

There also exist non-numerical constants, like:

'z'

'p'

"Hello world"

"How do you do?"

The first two expressions represent single character constants, and the following two represent string literals

composed of several characters. Notice that to represent a single character we enclose it between single quotes (')

and to express a string (which generally consists of more than one character) we enclose it between double quotes

(").

When writing both single character and string literals, it is necessary to put the quotation marks surrounding them

to distinguish them from possible variable identifiers or reserved keywords. Notice the difference between these

two expressions:

'x'

x alone would refer to a variable whose identifier is x, whereas 'x' (enclosed within single quotation marks) would

refer to the character constant 'x'.

Character and string literals have certain peculiarities, like the escape codes. These are special characters that are

difficult or impossible to express otherwise in the source code of a program, like newline (\n) or tab (\t). All of

them are preceded by a backslash (\). Here you have a list of some of such escape codes:

剩余143页未读，继续阅读

afeiluo

粉丝: 46
资源: 11

C++编程语言教程 - cplusplus.com 官方文档概述

c++学习文档

C++语言参考文档官方中文版

C/C++帮助文档

C++官方文档

opencv c++官方文档

C++库文件查询文档C++帮助文档

ISO C++ Standard：官方 C++ 标准文档，提供了详细的开发指南和 API 文档 C++ Documentati

C++开发文档

C++API文档

C++帮助文档

最新资源