5/2/2023 0 Comments C indirection operator![]() The expression expr is evaluated in place expression context. ![]() Related to the borrow operators are the raw address-of operators, which do not have first-class syntax, but are exposed via the macros ptr::addr_of!(expr) and ptr::addr_of_mut!(expr). `array` may only be used through `mutable_reference`.Įven though & is a single token ( the lazy 'and' operator), when used in the context of borrow expressions it works as two borrows: #! Mutably borrows `array` for this scope. a temporary with value 7 is created that lasts for this scope. If the & or &mut operators are applied to a value expression, then a temporary value is created. &mut evaluates its operand in a mutable place expression context. The memory location is also placed into a borrowed state for the duration of the reference.įor a shared borrow ( &), this implies that the place may not be mutated, but it may be read or shared again.įor a mutable borrow ( &mut), the place may not be accessed in any way until the borrow expires. When applied to a place expression, this expressions produces a reference (pointer) to the location that the value refers to. The & (shared borrow) and &mut (mutable borrow) operators are unary prefix operators. In rustc, these most negative expressions are also ignored by the overflowing_literals lint check. Negation of these most negative values leaves the value unchanged due to two's complement overflow conventions. In these cases, the literal expression already has the most negative value for its type (for example, 128_i8 has the value -128) because integer literals are truncated to their type per the description in Integer literal expressions. Note: The exception for literal expressions behind unary - means that forms such as -128_i8 or let j: i8 = -(128) never cause a panic and have the expected value of -128. Using > where the right-hand argument is greater than or equal to the number of bits in the type of the left-hand argument, or is negative.These checks occur even when -C overflow-checks is disabled, for legacy reasons. Using / or %, where the left-hand argument is the smallest integer of a signed integer type and the right-hand argument is -1.Applying unary - to the most negative value of any signed integer type, unless the operand is a literal expression (or a literal expression standing alone inside one or more grouped expressions).When +, * or binary - create a value greater than the maximum value, or less than the minimum value that can be stored. ![]() ![]() The following things are considered to be overflow: The -C debug-assertions and -C overflow-checks compiler flags can be used to control this more directly. Integer operators will panic when they overflow when compiled in debug mode. Many of the following operators can also be overloaded using traits in std::ops or std::cmp. Operators are defined for built in types by the Rust language. Macro Follow-Set Ambiguity Formal Specification ![]()
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