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Utilities

Example Topic
Optional std::optional instead of magic values, null pointers or exceptions
Algorithm <algorithm>, <numeric> and C++20 ranges/views
Regex <regex>: match, search, capture groups, replace
TypeTraits <type_traits>, the detection idiom, enable_if, C++20 concepts
Variadic C-style va_list vs variadic templates and fold expressions
Tuple tuples: make_tuple, get, tie, structured bindings, std::apply and returning several values (draft)
Any type-erased storage for a single value of any type, and when variant or optional fit better (draft)
Bitset a fixed-size sequence of bits: flags, counting, and conversion to strings and integers (draft)
Random <random>: engines, seeding, distributions, and why std::rand is not enough (draft)
Expected errors as values: expected<T, E>, and_then/transform, compared with optional and exceptions (draft)
Numeric <numeric>: iota, accumulate vs reduce, inner_product, partial_sum, gcd, lcm, midpoint (draft)
Ranges range algorithms, lazy views, pipelines, projections and ranges::to (draft)
SourceLocation capture the call site without macros, and print a stack trace (draft)
Span a non-owning view over contiguous memory: pointer + size in one type (draft)
Mdspan multidimensional views over flat storage: extents, layouts and accessors (draft)
Utility std::swap, std::exchange, std::as_const, integer comparisons and std::to_underlying (draft)

Utilities library

1. <optional>

There are several ways to represent "no value": - nullptr - sentinel values (-1, empty string, etc.) - exceptions - output parameters or flags

Drawbacks:

  • unclear semantics
  • unsafe assumptions
  • poor readability

optional was introduced to represent data that may be absent when that absence is part of the domain logic.

std::optional<std::string> name_opt = std::nullopt;

2. Variadic Functions (<cstdarg> / <stdarg.h>)

Variadic functions are functions that can take a variable number of arguments by declaring an ellipsis (...) after the parameter list.

e.g. int function(int a, ...);

  • To access the variadic arguments inside the function body, the following APIs are used:

va_start : initializes access to the variadic arguments va_arg : retrieves the next variadic argument va_copy : copies a variadic argument list va_end : ends traversal of the variadic arguments va_list : stores the information needed by va_start, va_arg, va_end, and va_copy