cpp / intermediate
Snippet
Static Template Branching with Constexpr If
The 'if constexpr' statement allows for compile-time branching. The branch not taken is discarded by the compiler, which is essential for template metaprogramming to avoid instantiating invalid code for certain types.
snippet.cpp
cpp
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
#include <iostream>#include <type_traits>template <typename T>void process_value(T val) {if constexpr (std::is_floating_point_v<T>) {std::cout << "Processing float: " << val << std::endl;} else {std::cout << "Processing non-float value" << std::endl;}}int main() {process_value(3.14); // Branches at compile-timeprocess_value(42); // Discards the float branchreturn 0;}
Breakdown
1
if constexpr (std::is_floating_point_v<T>)
Evaluates the condition at compile-time based on the template type.
2
std::cout << "Processing float: " << val << std::endl;
This line is only compiled into the binary if T is a floating-point type.