为什么这被认为是一个扩展的初始化列表? [英] Why is this considered an extended initializer list?
问题描述
#include< vector>
struct foo {
int i;
int j;
int k;
};
int main(){
std :: vector< foo> v(1);
v [0] = {0,0,0};
return 0;
}
当使用g ++编译时,我得到以下警告:
警告:扩展初始化器列表只能使用-std = c ++ 0x或-std = gnu ++ 0x [默认启用]
据我所知,它只是一个普通的初始化列表。该结构是一个POD类型。
这是一个错误还是我缺少某些东西?
Pre C ++ 11(和可能的C99)只能在创建时初始化POD,而不是在任意运行时点,这是你在这里尝试的(从初始化器列表中赋值)。
您可以使用null_foo:
int main $ b {
const foo null_foo = {0,0,0};
std :: vector< foo> v(1);
v [0] = null_foo;
return 0;
}
#include <vector>
struct foo {
int i;
int j;
int k;
};
int main() {
std::vector<foo> v(1);
v[0] = {0, 0, 0};
return 0;
}
When compiling this using g++, I get the following warning:
warning: extended initializer lists only available with -std=c++0x or -std=gnu++0x [enabled by default]
As far as I can tell, though, it's just a normal initializer list. The struct is a POD type.
Is this a bug or am I missing something?
Pre C++11 (and possibly C99) you can only initialize a POD at creation, not at arbitrary runtime points, which is what you're attempting here (assignment from an initializer list).
You can make a null_foo though:
int main()
{
const foo null_foo = {0, 0, 0};
std::vector<foo> v(1);
v[0] = null_foo;
return 0;
}
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