C++ Primer 学习笔记（3）——表达式

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#C++ Primer #理论学习

本文详细介绍了C++中的各类运算符，包括算术运算符、逻辑运算符等，并提供了丰富的示例代码。此外，还列举了C++运算符的优先级表。

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C++提供了一元操作符和二元操作符，另外还有三元操作符（三目操作符cond?expr1:exprl2）。

算术运算符

一元正号（+）返回操作数本身，对操作数不做任何修改。

逻辑运算符

存在短路求值。

优先级表如下：

Precedence	Operator	Description	Example	Associativity
1	() [] -> . :: ++ --	Grouping operator Array access Member access from a pointer Member access from an object Scoping operator Post-increment Post-decrement	(a + b) / 4; array[4] = 2; ptr->age = 34; obj.age = 34; Class::age = 2; for( i = 0; i < 10; i++ ) ... for( i = 10; i > 0; i-- ) ...	left to right
2	! ~ ++ -- - + * & (type) sizeof	Logical negation Bitwise complement Pre-increment Pre-decrement Unary minus Unary plus Dereference Address of Cast to a given type Return size in bytes	if( !done ) ... flags = ~flags; for( i = 0; i < 10; ++i ) ... for( i = 10; i > 0; --i ) ... int i = -1; int i = +1; data = *ptr; address = &obj; int i = (int) floatNum; int size = sizeof(floatNum);	right to left
3	->* .*	Member pointer selector Member pointer selector	ptr->var = 24; obj.var = 24;	left to right
4	* / %	Multiplication Division Modulus	int i = 2 * 4; float f = 10 / 3; int rem = 4 % 3;	left to right
5	+ -	Addition Subtraction	int i = 2 + 3; int i = 5 - 1;	left to right
6	<< >>	Bitwise shift left Bitwise shift right	int flags = 33 << 1; int flags = 33 >> 1;	left to right
7	< <= > >=	Comparison less-than Comparison less-than-or-equal-to Comparison greater-than Comparison geater-than-or-equal-to	if( i < 42 ) ... if( i <= 42 ) ... if( i > 42 ) ... if( i >= 42 ) ...	left to right
8	== !=	Comparison equal-to Comparison not-equal-to	if( i == 42 ) ... if( i != 42 ) ...	left to right
9	&	Bitwise AND	flags = flags & 42;	left to right
10	^	Bitwise exclusive OR	flags = flags ^ 42;	left to right
11	\|	Bitwise inclusive (normal) OR	flags = flags \| 42;	left to right
12	&&	Logical AND	if( conditionA && conditionB ) ...	left to right
13	\|\|	Logical OR	int i = (a > b) ? a : b	left to right
14	? :	Ternary conditional (if-then-else)	if( conditionA \|\| conditionB ) ...	right to left
15	= += -= *= /= %= &= ^= \|= <<= >>=	Assignment operator Increment and assign Decrement and assign Multiply and assign Divide and assign Modulo and assign Bitwise AND and assign Bitwise exclusive OR and assign Bitwise inclusive (normal) OR and assign Bitwise shift left and assign Bitwise shift right and assign	int a = b; a += 3; b -= 4; a *= 5; a /= 2; a %= 3; flags &= new_flags; flags ^= new_flags; flags \|= new_flags; flags <<= 2; flags >>= 2	right to left
16	,	Sequential evaluation operator	for( i = 0, j = 0; i < 10; i++, j++ ) ...	left to right