CPPAlliance

@CPPAlliance

Our mission is to make the C++ programming language accessible and useful to anyone who wishes to learn and apply the language.

CPPAlliance
@CPPAlliance
Oct 15
const char* s = "oops; By the letter of the standard, no diagnostic was required. It was undefined behavior Not at runtime. In the lexer. C++ had UB before your code was even parsed 🧵👇
2
CPPAlliance
@CPPAlliance
Oct 14
struct User { [[=Range{0, 150}]] int age; [[=NoSerialize{}]] std::string cache; }; That's valid C++26 (given those two structs). Your own metadata, attached to your own declarations, readable by your own code at compile time No macros. No code generator 🧵👇
2
CPPAlliance
@CPPAlliance
Oct 13
int total = a + b; if (total < a) { /* overflow? */ } Too late. If a + b overflowed, that was signed overflow, which is undefined behavior The compiler can assume it never happened and optimize your check away C++26 imports C23's answer 🧵👇
4
CPPAlliance
@CPPAlliance
Oct 12
Quick C++ quiz. What does the second line do? std::string s = load(); s.reserve(); Hint: C++20 deprecated it, and C++26 deletes it
3
CPPAlliance
@CPPAlliance
Oct 9
double x = std::generate_canonical<double, 53>(gen); Documented range: [0, 1) Rounding in the specified algorithm could still return exactly 1.0. Multiply by v.size() to pick an index and you read one past the end
2