在声明时初始化一个联合数组
我正在尝试在声明时初始化以下union数组：
typedef union { __m128d m; float f[4]; } mat; mat m[2] = { {{30467.14153,5910.1427,15846.23837,7271.22705}, {30467.14153,5910.1427,15846.23837,7271.22705}}}; 但是我发现了以下错误：
matrix.c: In function 'main': matrix.c:21: error: incompatible types in initialization matrix.c:21: warning: excess elements in union initializer matrix.c:21: warning: (near initialization for 'm[0]') matrix.c:21: warning: excess elements in union initializer matrix.c:21: warning: (near initialization for 'm[0]') matrix.c:21: warning: excess elements in union initializer matrix.c:21: warning: (near initialization for 'm[0]') matrix.c:21: error: incompatible types in initialization matrix.c:21: warning: excess elements in union initializer matrix.c:21: warning: (near initialization for 'm[1]') matrix.c:21: warning: excess elements in union initializer matrix.c:21: warning: (near initialization for 'm[1]') matrix.c:21: warning: excess elements in union initializer matrix.c:21: warning: (near initialization for 'm[1]')
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使用C89样式的初始值设定项，必须按声明的顺序初始化结构成员，并且只能初始化union的第一个成员。
所以，要么先将float数组放入，要么尽可能使用C99并写：
mat m[2] = { { .f = { /* and so on */ } }, /* ... */ };
重要的是.f 。
您需要指明要初始化的联合字段。 尝试使用以下语法：
mat m[2] = { {.f = {30467.14153,5910.1427,15846.23837,7271.22705}}, {.f = {30467.14153,5910.1427,15846.23837,7271.22705}} };
这成功为我编译，没有任何警告。
尝试更改成员：
typedef union { float f[4]; __m128d m; } mat; mat m[2] = { { {30467.14153,5910.1427,15846.23837,7271.22705}, {30467.14153,5910.1427,15846.23837,7271.22705} } };
如果初始化union而没有成员规范，如.f = {…}，则初始化union的第一个成员。