constexpr void square(int &x); // OK: declaration constexpr int bufsz = 1024; // OK: definition constexpr struct pixel { // error: pixel is a type int x; int y; constexpr pixel(int); // OK: declaration }; constexpr pixel::pixel(int a) : x(a), y(x) // OK: definition { square(x); } constexpr pixel small(2); // error: square not defined, so small(2) // not constant ([expr.const]) so constexpr not satisfied constexpr void square(int &x) { // OK: definition x *= x; } constexpr pixel large(4); // OK: square defined int next(constexpr int x) { // error: not for parameters return x + 1; } extern constexpr int memsz; // error: not a definition— end example
constexpr int square(int x)
{ return x * x; } // OK
constexpr long long_max()
{ return 2147483647; } // OK
constexpr int abs(int x) {
if (x < 0)
x = -x;
return x; // OK
}
constexpr int first(int n) {
static int value = n; // error: variable has static storage duration
return value;
}
constexpr int uninit() {
int a; // error: variable is uninitialized
return a;
}
constexpr int prev(int x)
{ return --x; } // OK
constexpr int g(int x, int n) { // OK
int r = 1;
while (--n > 0) r *= x;
return r;
} — end example
struct Length {
constexpr explicit Length(int i = 0) : val(i) { }
private:
int val;
}; — end example
constexpr int f(bool b)
{ return b ? throw 0 : 0; } // OK
constexpr int f() { return f(true); } // ill-formed, no diagnostic required
struct B {
constexpr B(int x) : i(0) { } // x is unused
int i;
};
int global;
struct D : B {
constexpr D() : B(global) { } // ill-formed, no diagnostic required
// lvalue-to-rvalue conversion on non-constant global
}; — end exampleconstexpr int bar(int x, int y) // OK { return x + y + x*y; } // ... int bar(int x, int y) // error: redefinition of bar { return x * 2 + 3 * y; }— end example
struct pixel {
int x, y;
};
constexpr pixel ur = { 1294, 1024 }; // OK
constexpr pixel origin; // error: initializer missing
— end example