I found the problem when initializing a vector with value -2147483648
vector<int> vec1({-2147483648}); // invalid, error C2440
vector<int> vec2({0, -2147483648}); // invalid, error C2398
int a = -2147483648;
vector<int> vec3({t}); // valid
vector<int> vec4({0, t}); // valid
vector<int> vec5(1, -2147483648); // valid
The problem appears when I use VS2013. Does anyone know why?
-2147483648
is a unary negation operator applied to an integral literal 2147483648
. The latter does not fit into an int
(assuming it's 32-bit), which means that -2147483648
is actually an expression of unsigned
type.
Now, unsigned
can be implicitly converted to int
(when the value is unrepresentable, the result is technically implementation-defined, but usually unsurprising). However, this is a narrowing conversion, which is prohibited when used with brace initialization.
Instead of attempting to write the value as a literal, just use INT_MIN
from the <limits.h>
header, or std::numeric_limits<int>::min()
from the <limits>
header, assuming that your intention is to express the minimum value of an int
.
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