技术术语instruction与operation之间的区别是什么？

Let's break down these core computing terms clearly, with concrete examples tied to C++ and x86 assembly to make things easy to follow:

Instruction: The Atomic Unit of Assembly #

An instruction is the smallest, indivisible command a CPU can execute directly—it's the fundamental building block of assembly language.
Example:
MOV EAX, EBX — This x86 instruction copies the value stored in the EBX register to the EAX register.

Operator: Symbols for Computation in High-Level Languages #

In languages like C++, an operator is a symbol that represents a specific action or computation.
Take this simple C++ snippet:

int a = 1;
int b = a + 3;

Here, both = (assignment) and + (addition) are operators.

Operation: The Result of Executing an Operator #

First, let's start with the mathematical definition:

In mathematics, an operation is a function that takes zero or more input values (called operands) and produces a well-defined output value.

From a computer science perspective, I believe an operator doesn't have practical execution value without being tied to an action that uses its result. For example, you could write b > c; in C++—it's syntactically valid, but it does nothing useful because there's no assignment or side effect to leverage the comparison result. Even increment/decrement operators like ++x work internally like x = x + 1 under the hood.

So in computer science terms:
An operation is the result of a single operator being executed.

Operation Examples #

• c = 1 + 2; — This counts as one operation, since it only uses a single + operator.
• c = 1 + 2 + 3; — This contains two operations: first 1 + 2, then adding that result to 3.

Mapping Operations to x86 Instructions #

It's crucial to note that a single line of high-level code doesn't always translate to one assembly instruction. Let's revisit our earlier C++ example:

int a = 1;
int b = a + 3;

When compiled to x86 assembly, this might become:

MOV EAX, 1        ; Corresponds to int a = 1;
ADD EAX, 3        ; First part of int b = a +3: add 3 to a's value (stored in EAX)
MOV EBX, EAX      ; Store the final result in EBX (for variable b)

For x86 specifically, we can refine the operation definition:
An operation is the result of an operator being executed, and it translates to one or more assembly instructions.

内容的提问来源于stack exchange，提问作者No Name QA