|
- What is the lt;= gt; (spaceship, three-way comparison) operator in C++?
This is called the three-way comparison operator According to the P0515 paper proposal: There’s a new three-way comparison operator, <=> The expression a <=> b returns an object that compares <0 if a < b, compares >0 if a > b, and compares ==0 if a and b are equal equivalent To write all comparisons for your type, just write operator<=> that returns the appropriate category type: Return
- C++ code file extension? What is the difference between . cc and . cpp
95 cpp is the recommended extension for C++ as far as I know Some people even recommend using hpp for C++ headers, just to differentiate from C Although the compiler doesn't care what you do, it's personal preference
- What does the :: mean in C++? - Stack Overflow
What does this symbol mean? AirlineTicket::AirlineTicket ()@PaulR Not everyone who arrives upon this question is looking to learn C++ I, for example, just happened to be skimming some C++ code and wanted to get the general idea of what the program is doing and needed a quick reference :)
- Why are #ifndef and #define used in C++ header files?
I have been seeing code like this usually in the start of header files: #ifndef HEADERFILE_H #define HEADERFILE_H And at the end of the file is #endif What is the purpose of this?
- how does the ampersand( ) sign work in c++? - Stack Overflow
Possible Duplicate: What are the differences between pointer variable and reference variable in C++? This is confusing me: class CDummy { public: int isitme (CDummy amp; param); }; int CD
- How can I convert int to string in C++? - Stack Overflow
itoa will be faster than the stream equivalent There are also ways of re-using the string buffer with the itoa method (avoiding heap allocations if you are frequently generating strings e g for some rapidly updating numerical output) Alternatively you can generate a custom streambuf to reduce some of the allocation overhead etc Constructing the stream in the first place is also not a low
- How to find if a given key exists in a std::map - Stack Overflow
To those who are looking for speed: count and find are nearly identical in speed when using maps that require unique keys (1) If you don't need the elements to maintain a specific order, use std::unordered_map, which has near-constant look-ups and can be very beneficial when storing more than a few pairs (2) If you want to use the value if it exists, store the result of ::find and use the
- What is the purpose of using #ifdef and #if in C++?
The meaning of #ifdef is that the code inside the block will be included in the compilation only if the mentioned preprocessor macro is defined Similarly, #if means that the block will be included only if the expression evaluates to true (when replacing undefined macros that appears in the expression with 0) One important point here is that the preprocessor processes the source before it's
|
|
|