Union Structure数组的初始化太多了

Question

这段代码只是为了测试我对结构数组访问的了解.当我执行这段代码时,它给了我两个很多初始化参数的错误.请帮助我理解错误并解决此问题.我试图重用已经由某人解决的代码.关于用参数Param_u param填充Struct的问题

#include <iostream>
#include <stdio.h>
#include <string.h>


#define ARRAY_COUNT(arr) (sizeof (arr) / sizeof *(arr))

typedef union {
    struct {    // Function parameters
        int *array;
        size_t size;
    };
    struct {    // Function return value
        float mean;
        int Median;
    };
} Param_u;

int main() {
    int array_1[] = {1, 2, 3, 4, 5};
    int  ret1, ret2;

    // Fill the Struct with parameters
    Param_u param = {
        .array = array_1,
        .size = ARRAY_COUNT(array_1),
    };
    return 0;
}

Answer 1

这不是标准的 C++。您正在使用匿名struct和指定的初始值设定项（C99 功能）。C++ 不支持这一点。启用-pedantic-errorsclang++ & 上的选项g++。请参阅此问题了解更多详细信息。您正在使用编译器特定的扩展，因此您的程序不可移植。

请参阅此处的现场演示。

clang++给出以下诊断：

Error(s):

source_file.cpp:12:5: error: anonymous structs are a GNU extension [-Werror,-Wgnu-anonymous-struct]
    struct {    // Function parameters
    ^
source_file.cpp:16:5: error: anonymous structs are a GNU extension [-Werror,-Wgnu-anonymous-struct]
    struct {    // Function return value
    ^
source_file.cpp:28:9: error: designated initializers are a C99 feature [-Werror,-Wc99-extensions]
        .array = array_1,
        ^~~~~~~~~~~~~~~~
source_file.cpp:29:9: error: designated initializers are a C99 feature [-Werror,-Wc99-extensions]
        .size = ARRAY_COUNT(array_1),
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
source_file.cpp:24:16: warning: unused variable 'ret2' [-Wunused-variable]
    int  ret1, ret2;
               ^
source_file.cpp:27:13: warning: unused variable 'param' [-Wunused-variable]
    Param_u param = {
            ^
source_file.cpp:24:10: warning: unused variable 'ret1' [-Wunused-variable]
    int  ret1, ret2;
         ^
3 warnings and 4 errors generated.