C++ container printer - CPPCP

Printing in C++ with IOstream is quite cumbersome and inconvenient. C++ also does not have a default output for containers (only available with std::print in C++23). Printing nested containers is even more difficult. This library provides a simple solution for fast debug printing (with competitive programming in mind).

About

CPPCP is a header file providing 2 (overloaded/templatized) functions

• print - Prints and formats a (nested) container (or a basic type)
• printx - Formats a string, replacing {} with formatted values

The print function relies on having a special overload for any special type. Hence it can be simply extended by providing overload for an additional type (custom struct/class) or for a specific pair/tuple.

Supported types

All basic types that std::ostream can print are supported, some are printed a bit differently. bool is printed as true/false, std::string/const char* is printed with quotes. Arbitrary std::pair and std::tuple are also supported. Iterators can also be printed (prints the value with IT prefix).

Containers All the basic containers from STL are included. More specifically: std::array, std::vector, std::stack, std::queue, std::deque, std::list, std::forward_list, std::map, std::unordered_map, std::set, std::unordered_set, std::multimap, std::unordered_multimap, std::multiset, std::unordered_multiset, std::priority_queue.

Future TODO

• Add support for the remaining containers/adaptors/views: std::span, std::flat_map, std::flat_set, std::flat_multimap, std::flat_multiset, std::mdspan (more are C++23 only).
• Make an optional way to print std::vector/std::array with indices
• Make printx work without any interpolated value
• Add support for C style arrays

Example usage

Array of Tuples:

std::vector<std::tuple<int,bool,std::string>> tuple_arr({{17, false, "First"}, {-5, true, "Second"}});
printx("Content: {}", tuple_arr);

Will print:

Content: V[T(17, false, "First"), T(-5, true, "Second")]

2D array:

vector<vector<int>> array2d({{1, 5, 7, 2, 6}, {0}, {3, 1, 4}});
print(array2d);

Will print:

V[
  V[1, 5, 7, 2, 6]
  V[0]
  V[3, 1, 4]
]

Map with list

std::map<std::pair<int, int>, std::list<std::string>> tasks({{{5, 4}, {"Cleaning", "Dinner"}}, {{7, 2}, {"Hiking"}}});
print(tasks);

Will print:

M{
  P(5, 4) -> DL<("Cleaning") <-> ("Dinner")>
  P(7, 2) -> DL<("Hiking")>
}