Comments
Comments serve as a sort of in-code documentation. When inserted into a program, they are effectively ignored by the compiler; they are solely intended to be used as notes by the humans that read source code. Although specific documentation is not part of the C++ standard, several utilities exist that parse comments with different documentation formats.
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[edit] Syntax
/* comment */
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// comment\n
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1) Often known as "C-style" or "multi-line" comments.
2) Often known as "C++-style" or "single-line" comments.
[edit] C-style
C-style comments are usually used to comment large blocks of text, however, they can be used to comment single lines. To insert a C-style comment, simply surround text with /* and */; this will cause the contents of the comment to be ignored by the compiler. Although it is not part of the C++ standard, /** and */ are often used to indicate documentation blocks; this is legal because the second asterisk is simply treated as part of the comment. C-style comments cannot be nested.
C-style comments are often preferred in environments where C and C++ code may be mixed, because they are the only form of comment that can be used in the C standard (prior to C99).
[edit] C++-style
C++-style comments are usually used to to comment single lines, however, multiple C++-style comments can be placed together to form multi-line comments. C++-style comments tell the compiler to ignore all content between // and a new line, which makes them very useful.
[edit] Example
/* C-style comments can contain multiple lines */ /* or just one */ // C++-style comments can comment one line // or, they can // be strung together int main() { // The below code won't be run // return 1; // The below code will be run return 0; }