Increment/decrement operators

 

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C + +语言

大会的主题 Original: General topics The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
预处理器 评论 关键字	ASCII表 转义序列 C + +的历史
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存储时间说明符
constexpr说明 （C++11）
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alignas说明 （C++11）
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常 Original: Literals The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
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价值类型 为了评价	运营商 运算符的优先级
另一种表示形式
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隐式转换
const_cast conversion
static_cast conversion
dynamic_cast conversion
reinterpret_cast conversion
C-风格和功能转换
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new expression	delete expression
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内联汇编

 

递增/递减运算符递增或递减的对象的值.

Original:

Increment/decrement operators increments or decrements the value of the object.

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Operator name	Syntax	Over​load​able	Prototype examples (for class T)
			Inside class definition	Outside class definition
pre-increment	++a	Yes	T& T::operator++();	T& operator++(T& a);
pre-decrement	--a	Yes	T& T::operator--();	T& operator--(T& a);
post-increment	a++	Yes	T T::operator++(int);	T operator++(T& a, int);
post-decrement	a--	Yes	T T::operator--(int);	T operator--(T& a, int);
注意 Original: Notes The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. 前缀形式的内置在运营商的返回引用和后缀形式返回值，和典型的用户定义的重载跟随模式，使用户定义的运算可以用在相同的方式内置插件。然而，在一个用户定义的操作符重载，任何类型都可以被用作返回类型（包括void）. Original: Prefix forms of the built-in operators return references and postfix forms return values, and typical user-defined overloads follow the pattern so that the user-defined operators can be used in the same manner as the built-ins. However, in a user-defined operator overload, any type can be used as return type (including void). The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. int参数是一个虚拟参数，用来区分前和后的版本的运营商。当用户定义的后缀运算符被调用时，在该参数传递的值始终为零，虽然它可能被改变了调用函数调用表示法的操作员使用，例如a.operator++(2). Original: The int parameter is a dummy parameter used to differentiate between pre- and post- in versions of the operators. When the user-defined postfix operator is called, the value passed in that parameter is always zero, although it may be changed by calling the operator using function call notation, e.g. a.operator++(2). The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

解释

“前增加”和“预减”运营商增加或减小该值的对象，并返回一个引用到的结果.....

Original:

pre-increment and pre-decrement operators increments or decrements the value of the object and returns a reference to the result.

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“后增加”和“减”创建一个副本的对象，递增或递减的对象的值，并返回从之前的增量或减量的副本.

Original:

post-increment and post-decrement creates a copy of the object, increments or decrements the value of the object and returns the copy from before the increment or decrement.

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内置的前缀运算符

对于每一个可以用volatile限定A以外bool，并为每个可以用volatile限定P可以用CV合格的对象类型的指针，下面的函数签名参与重载解析：算术类型

Original:

For every optionally volatile-qualified arithmetic type A other than bool, and for every optionally volatile-qualified pointer P to optionally cv-qualified object type, the following function signatures participate in overload resolution:

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A& operator++(A&)
bool& operator++(bool&)		（过时了）
P& operator++(P&)
A& operator--(A&)
P& operator--(P&)

一个内置的前缀递增或递减运算的操作数必须是一个可修改的左值（非const引用）的非布尔值的算术类型或对象类型的指针完成。这些操作数，表达++x是完全等同于x+=1，--x，这是完全等同的表达x-=1，其结果是更新操作，返回的左值，所有的算术转换规则和指针运算规则定义算术运算符申请.

Original:

The operand of a built-in prefix increment or decrement operator must be a modifiable lvalue (non-const reference) of non-boolean arithmetic type or pointer to complete object type. For these operands, the expression ++x is exactly equivalent to x+=1, and the expression --x is exactly equivalent to x-=1, that is, the result is the updated operand, returned as lvalue, and all arithmetic conversion rules and pointer arithmetic rules defined for 算术运算符 apply.

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如果操作数的前递增运算符类型bool，它被设置为true（过时了）.

Original:

If the operand of the preincrement operator is of type bool, it is set to true （过时了）.

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内置的后缀运算符

对于每一个可以用volatile限定A以外bool，并为每个可以用volatile限定P可以用CV合格的对象类型的指针，下面的函数签名参与重载解析：算术类型

Original:

For every optionally volatile-qualified arithmetic type A other than bool, and for every optionally volatile-qualified pointer P to optionally cv-qualified object type, the following function signatures participate in overload resolution:

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A operator++(A&, int)
bool operator++(bool&, int)		（过时了）
P operator++(P&, int)
A operator--(A&, int)
P operator--(P&, int)

一个内置的后缀递增或递减运算的操作数必须是一个可修改的左值（非const引用）的非布尔值的算术类型或对象类型的指针完成。其结果是一个prvalue，这是复制的原始值的操作数。作为一个副作用，该运营商修改其参数值arg如果通过评估arg += 1或arg -= 1，分别为递增和递减。所有的算术转换规则和指针运算规则定义算术运算符申请.

Original:

The operand of a built-in postfix increment or decrement operator must be a modifiable lvalue (non-const reference) of non-boolean arithmetic type or pointer to complete object type. The result is a prvalue, which is a copy the original value of the operand. As a side-effect, this operator modifies the value of its argument arg as if by evaluating arg += 1 or arg -= 1, for increment and decrement respectively. All arithmetic conversion rules and pointer arithmetic rules defined for 算术运算符 apply.

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如果类型bool的后递增操作符的操作数，它被设置为true（过时了）.

Original:

If the operand of the postincrement operator is of type bool, it is set to true （过时了）.

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为例

#include <iostream>
int main()
{
    int n = 1;
    int n2 = ++n;
    int n3 = ++ ++n;
    int n4 = n++;
//    int n5 = n++ ++; // compile error
//    int n5 = n + ++n; // undefined behavior
    std::cout << "n = " << n << '\n'
              << "n2 = " << n2 << '\n'
              << "n3 = " << n3 << '\n'
              << "n4 = " << n4 << '\n';
}

Output:

n = 5
n2 = 2
n3 = 4
n4 = 4

注释

由于副作用参与，内置的增量和减量运算，必须谨慎使用，以避免不确定的行为因违反排序规则.

Original:

Because of the side-effects involved, built-in increment and decrement operators must be used with care to avoid undefined behavior due to violations of 排序规则.

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在操作过程中，因为临时对象的拷贝构造“前增加”或“预减”运营商在不使用的上下文中返回的值通常更有效.

Original:

Because a temporary copy of the object is constructed during the operation, pre-increment or pre-decrement operators are usually more efficient in contexts where the returned value is not used.

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标准库

递增和递减运算符重载，许多标准库类型。特别是，每一个Iterator重载运算符+ +和每BidirectionalIterator重载运算符 - ，即使这些运营商没有特定的迭代器操作.

Original:

Increment and decrement operators are overloaded for many standard library types. In particular, every Iterator overloads operator++ and every BidirectionalIterator overloads operator--, even if those operators are no-ops for the particular iterator.

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算术类型的重载 Original: overloads for arithmetic types The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
operator++ operator++(int) operator-- operator--(int)	递增或递减一个原子值 Original: increments or decrements the atomic value by one The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （公共成员函数of std::atomic）
operator++ operator++(int) operator-- operator--(int)	递增或递减滴答计数 Original: increments or decrements the tick count The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （公共成员函数of std::chrono::duration）
迭代器类型的重载 Original: overloads for iterator types The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
operator++ operator++(int)	进步的迭代器 Original: advances the iterator The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （公共成员函数of std::raw_storage_iterator）
operator++ operator++(int)	进步的迭代器 Original: advances the iterator The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （公共成员函数of std::reverse_iterator）
operator-- operator++(int)	减少了迭代器 Original: decrements the iterator The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （公共成员函数of std::reverse_iterator）
operator++ operator++(int)	no-op （公共成员函数of std::back_insert_iterator）
operator++ operator++(int)	no-op （公共成员函数of std::front_insert_iterator）
operator++ operator++(int)	no-op （公共成员函数of std::insert_iterator）
operator++ operator++(int)	进步的迭代器 Original: advances the iterator The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （公共成员函数of std::move_iterator）
operator-- operator--(int)	减少了迭代器 Original: decrements the iterator The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （公共成员函数of std::move_iterator）
operator++ operator++(int)	推进istream_iterator Original: advances the istream_iterator The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （公共成员函数of std::istream_iterator）
operator++ operator++(int)	no-op （公共成员函数of std::ostream_iterator）
operator++ operator++(int)	推进istreambuf_iterator Original: advances the istreambuf_iterator The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （公共成员函数of std::istreambuf_iterator）
operator++ operator++(int)	no-op （公共成员函数of std::ostreambuf_iterator）
operator++ operator++(int)	推进regex_iterator Original: advances the regex_iterator The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （公共成员函数of std::regex_iterator）
operator++ operator++(int)	推进regex_token_iterator Original: advances the regex_token_iterator The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （公共成员函数of std::regex_token_iterator）

另请参阅

运算符优先级

Common operators
分配	incrementNJdecrement	算术	合乎逻辑的	比较	memberNJaccess	其他
a = b a = rvalue a += b a -= b a *= b a /= b a %= b a &= b a |= b a ^= b a <<= b a >>= b	++a --a a++ a--	+a -a a + b a - b a * b a / b a % b ~a a & b a | b a ^ b a << b a >> b	!a a && b a || b	a == b a != b a < b a > b a <= b a >= b	a[b] *a &a a->b a.b a->*b a.*b	a(...) a, b (type) a ? :
Special operators
static_cast将一种类型转换到另一个兼容的类型 Original: static_cast converts one type to another compatible type The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. dynamic_cast将虚基类到派生class Original: dynamic_cast converts virtual base class to derived class The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. const_cast转换类型兼容型，与不同的cvqualifiers Original: const_cast converts type to compatible type with different cv qualifiers The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. reinterpret_cast转换类型不兼容的type Original: reinterpret_cast converts type to incompatible type The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. new个分配memory Original: new allocates memory The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. delete会释放memory Original: delete deallocates memory The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. sizeof查询的大小的type Original: sizeof queries the size of a type The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. sizeof...查询的大小的参数组（C++11 起） Original: sizeof... queries the size of a 参数组 （C++11 起） The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. typeid查询的类型一个type 信息 Original: typeid queries the type information of a type The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. noexcept进行检查，，如果的表达可以抛出一个异常（C++11 起） ， Original: noexcept checks if an expression can throw an exception （C++11 起） The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. alignof查询类型（C++11 起）对齐要求 Original: alignof queries alignment requirements of a type （C++11 起） The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.