What is the difference between templates and macros in C++?

Point	Template	Macro
Done by	Compiler	Preprocessor (text)
Type safe	Yes	No
Scope and namespaces	Yes	No
Debugging	Normal	Hard
Side effects	None	Arguments can be evaluated twice

#include <iostream>

#define SQUARE(x) x * x

template <typename T>
constexpr T square(T x) { return x * x; }

int main() {
    int n = 3;
    std::cout << SQUARE(n + 1) << '\n';          // becomes n + 1 * n + 1 = 7: a macro bug
    std::cout << square(n + 1) << '\n';          // 16: correct
}

Use constexpr, const, templates and inline functions instead of macros. Macros stay useful for include guards and conditional compiling. See Templates.

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