> ## Documentation Index
> Fetch the complete documentation index at: https://docs.syntblaze.com/llms.txt
> Use this file to discover all available pages before exploring further.
# C++ Single-line Comment
A single-line comment in C++ is a lexical construct that instructs the compiler to ignore all text following the comment delimiter up to the end of the current line. During the early translation phases of C++, the preprocessor strips these comments from the source code, typically replacing them with a single whitespace character before syntactic analysis begins.
```cpp theme={"dark"}
// comment_text
```
**Syntactic Mechanics**
* **Initiation:** The comment is initiated by two consecutive forward slashes (`//`) with no intervening whitespace.
* **Termination:** The comment is implicitly terminated by the next newline character (`\n`). No explicit closing delimiter is required.
* **Parsing:** The compiler evaluates the code strictly from left to right. Once the `//` token is encountered, all subsequent characters on that physical line are treated as part of the comment, regardless of whether they resemble valid C++ syntax.
```cpp theme={"dark"}
// This is a standalone single-line comment.
int x = 10; // This comment follows a valid statement.
```
**Line Splicing (Continuation)**
Because C++ processes physical source lines into logical lines during phase 2 of translation (before comments are removed in phase 3), a single-line comment can be extended to the next physical line using a backslash (`\`). If the backslash is immediately followed by a newline character, the compiler splices the lines together, extending the single-line comment.
```cpp theme={"dark"}
// This comment is extended to the next physical line \
and the compiler will ignore this text as well.
int y = 20;
```
**Nesting Behavior**
Single-line comments do not possess nesting semantics. Because everything after the `//` is treated as raw text, placing another `//` or a block comment initiator (`/*`) inside a single-line comment has no syntactic effect; it is simply absorbed as part of the ignored text.
```cpp theme={"dark"}
// // This second delimiter is ignored.
// /* This block comment initiator is also ignored.
```
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