2 min read
Floating-point operators
Floating-point operators For floating-point and complex numbers, +x is the same as x, while -x is the negation of x. The result of a floating-point or complex division by zero is not specified beyond the IEEE-754 standard; whether a run-time panic occurs is implementation-specific. I find this to be quite interesting. An implementation may choose to panic, or not, if you attempt to divide a floating-point or complex number by zero.
2 min read
Integer overflow
Integer overflow For unsigned integer values, the operations +, -, *, and << are computed modulo 2n, where n is the bit width of the unsigned integer’s type. Loosely speaking, these unsigned integer operations discard high bits upon overflow, and programs may rely on “wrap around”. Let’s illustrate with an example. I’ll use uint8, becuase it’s easier to reason about relatively small numbers, but the same holds for any of the uint family of types.
1 min read
Can you think of an use case for ^x?
Last week I talked about unary integer operators, including the ^ operator. A reader wrote back asking: Can you think of an use case for ^x? So today I’m going to answer this question! No! LOL Not very satisfying, is it? So I did some digging to find some examples. Note, none of these are my own examples. This is something most of us will never use. But it’s a good question nonetheless.
21 min watch
FOSDEM 2024: You're already running my code in production
How I became a Go contributor, and you can, too.
2 min read
Unary integer operators
We have a quick one today to finish up integer operators, before diving into a semi-hairy topic next… Integer operators … For integer operands, the unary operators +, -, and ^ are defined as follows: +x is 0 + x -x negation is 0 - x ^x bitwise complement is m ^ x with m = "all bits set to 1" for unsigned x and m = -1 for signed x So the first two are pretty obvious… + and - just allow you to specify the sign of a thing.
2 min read
Divide by zero, and shifting
Integer operators … If the divisor is a constant, it must not be zero. If the divisor is zero at run time, a run-time panic occurs. I’m sure you expected that. Division by zero is pretty universally not allowed. var a = 3 var b = 0 var c = a / 0 // Won't compile var d = a / b // run-time panic … If the dividend is non-negative and the divisor is a constant power of 2, the division may be replaced by a right shift, and computing the remainder may be replaced by a bitwise AND operation:
2 min read
Integer operators
Today we continue our discussion of arithmetic operators, with a topic that is likely not new to you at all: Integer operators. Integer operators For two integer values x and y, the integer quotient q = x / y and remainder r = x % y satisfy the following relationships: x = q*y + r and |r| < |y| This should be pretty obvious and intuitive… If you divide x / y and get a quotiont q and remainder r, then multiplying q * y and adding r should reveal x again.
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1 min read
Join me at FOSDEM
Do you have plans to be in Brussels this weekend? If so, join me at FOSDEM 2024! I’ll be speaking in the Go Devroom on Saturday morning on my journey to becoming a Go contributor. Not going to be in Brussels? Follow me on Mastodon where I’ll be live micro-blogging from the event, and stick around for links to a video of my presentation when it’s made available.
2 min read
Arithmetic operators
Arithmetic operators Arithmetic operators apply to numeric values and yield a result of the same type as the first operand. The four standard arithmetic operators (+, -, *, /) apply to integer, floating-point, and complex types; + also applies to strings. The bitwise logical and shift operators apply to integers only. + sum integers, floats, complex values, strings - difference integers, floats, complex values * product integers, floats, complex values / quotient integers, floats, complex values % remainder integers & bitwise AND integers | bitwise OR integers ^ bitwise XOR integers &^ bit clear (AND NOT) integers << left shift integer << integer >= 0 >> right shift integer >> integer >= 0 There should be nothing surprising here.
2 min read
Operator precedence
I hope we all know what operator precedence means… but just in case it’s fuzzy, I’ll illustrate with a simple example from junior high school. What does this mean? 1 + 2 * 3 It’s either 9 or 7, right? It depends on the order in which we apply the + and * operations. I’m sure most of us agree that the correct answer is actually 7, because multiplication takes precedence over addition.
3 min read
Shift operators
Operators … The right operand in a shift expression must have integer type or be an untyped constant representable by a value of type uint. A bunch of examples demonstrating this follow in the spec, so I won’t provide my own. … If the left operand of a non-constant shift expression is an untyped constant, it is first implicitly converted to the type it would assume if the shift expression were replaced by its left operand alone.