diff --git a/README.md b/README.md
index 9f9efe1..f2c55e1 100644
--- a/README.md
+++ b/README.md
@@ -5,7 +5,7 @@
* Convert any integral type to a string at compile-time
* Supports converting to any base between 2 and 36 inclusive
* No external dependencies, only includes `type_traits` for template parameter checking
-* Works best in C++20 GCC or C++17/20 Clang
+* Supports custom character types, e.g. `to_string<123, 10, wchar_t>`
**How to use:**
@@ -22,31 +22,31 @@ With `to_string`, all that will be found in program disassembly are the resultin
Try it [on Compiler Explorer](https://godbolt.org/z/T-MFoh).
-**Known issues:**
-
-* With C++17 GCC, `to_string` must be used to initialize variables; otherwise, the integer-string conversion is done at run-time.
-
# How it works
The basic structure of `to_string` is shown below:
```cpp
-template
+template
struct to_string_t {
- char buf[]; // Size selection explained later.
- constexpr to_string_t() {} // Converts the integer to a string stored in buf.
- constexpr operator char *() {} // These allow for the object to be implicitly converted
- constexpr operator const char *() {} // to a character pointer.
+ char_type buf[]; // Size selection explained later.
+ constexpr to_string_t() {} // Converts the integer to a string stored in buf.
+ constexpr operator char_type *() {} // These allow for the object to be implicitly converted
+ constexpr operator const char_type *() {} // to a character pointer.
+
+ // begin() and end() are supported too.
};
-template
-to_string_t to_string; // Simplifies usage: to_string_t() becomes to_string.
+template
+constexpr to_string_t to_string; // Simplifies usage, e.g. to_string_t<367>() becomes to_string<367>.
```
Since the number and base are template parameters, each differing `to_string` use will get its own character buffer.
The integer/string conversion is done using a simple method I learned over the years, where the string is built in reverse using `n % base` to calculate the value of the lowest digit:
+(*Note: The below examples of code are not up-to-date, though they still give a general idea of how `to_string` works.*)
+
```cpp
constexpr to_string_t() {
auto ptr = buf + sizeof(buf) / sizeof(buf[0]);
diff --git a/to_string.hpp b/to_string.hpp
index 6117258..bf724cd 100644
--- a/to_string.hpp
+++ b/to_string.hpp
@@ -15,49 +15,60 @@
* @tparam N Number to convert
* @tparam base Desired base, can be from 2 to 36
*/
-template, int> = 0,
std::enable_if_t<(base > 1 && base < 37), int> = 0>
-struct to_string_t {
+class to_string_t {
// The lambda calculates what the string length of N will be, so that `buf`
// fits to the number perfectly.
- char buf[([] {
- unsigned int len = N >= 0 ? 1 : 2;
- for (auto n = N; n; len++, n /= base);
- return len;
- }())];
+ char_type buf[([]() constexpr noexcept {
+ unsigned int len = N > 0 ? 1 : 2;
+ for (auto n = N; n; len++, n /= base);
+ return len;
+ }())] = {};
+ public:
/**
* Constructs the object, filling `buf` with the string representation of N.
*/
- constexpr to_string_t() {
- auto ptr = buf + sizeof(buf) / sizeof(buf[0]);
+ constexpr to_string_t() noexcept {
+ auto ptr = end();
*--ptr = '\0';
- for (auto n = N; n; n /= base)
- *--ptr = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"[(N < 0 ? -1 : 1) * (n % base)];
- if (N < 0)
- *--ptr = '-';
+ if (N != 0) {
+ for (auto n = N < 0 ? -N : N; n; n /= base)
+ *--ptr = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"[(N < 0 ? -1 : 1) * (n % base)];
+ if (N < 0)
+ *--ptr = '-';
+ } else {
+ buf[0] = '0';
+ }
}
- /**
- * Allows implicit conversion of this object to a `char *`.
- */
- constexpr operator char *() {
- return buf;
- }
-
- /**
- * Allows implicit conversion of this object to a `const char *`.
- */
- constexpr operator const char *() const {
- return buf;
- }
+ // Support implicit casting to `char *` or `const char *`.
+ constexpr operator char_type *() noexcept { return buf; }
+ constexpr operator const char_type *() const noexcept { return buf; }
+
+ constexpr auto size() const noexcept { return sizeof(buf) / sizeof(buf[0]); }
+ // Element access
+ constexpr auto data() noexcept { return buf; }
+ constexpr const auto data() const noexcept { return buf; }
+ constexpr auto& operator[](unsigned int i) noexcept { return buf[i]; }
+ constexpr const auto& operator[](unsigned int i) const noexcept { return buf[i]; }
+ constexpr auto& front() noexcept { return buf[0]; }
+ constexpr const auto& front() const noexcept { return buf[0]; }
+ constexpr auto& back() noexcept { return buf[size() - 1]; }
+ constexpr const auto& back() const noexcept { return buf[size() - 1]; }
+ // Iterators
+ constexpr auto begin() noexcept { return buf; }
+ constexpr const auto begin() const noexcept { return buf; }
+ constexpr auto end() noexcept { return buf + size(); }
+ constexpr const auto end() const noexcept { return buf + size(); }
};
/**
* Simplifies use of `to_string_t` from `to_string_t()` to `to_string`.
*/
-template
-to_string_t to_string;
-
+template
+constexpr to_string_t to_string;
+
#endif // TCSULLIVAN_TO_STRING_HPP_