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- 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
- 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
- What is the proper declaration of main in C++? - Stack Overflow
This question is not an exact duplicate of the What should main () return in C and C++? However, everything that it asks is already answered over there in greater detail and in greater quality, which makes this question a duplicate This question is also problematic in its current state because it's not very focused, and is asking about system-specifics, historical changes, and all sorts of
- 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
- What does the C++ standard say about the size of int, long?
I'm looking for detailed information regarding the size of basic C++ types I know that it depends on the architecture (16 bits, 32 bits, 64 bits) and the compiler But are there any standards for
- How to generate a random number in C++? - Stack Overflow
I'm trying to make a game with dice, and I need to have random numbers in it (to simulate the sides of the die I know how to make it between 1 and 6) Using #include lt;cstdlib gt; #include lt;
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