C++ error: expected primary-expression before ‘.’ token

Question

I looked at the earlier questions but still i was not satisfied, hence i am posting this. I was trying to compile the C++ code written by someone else.

/*
file1.h
*/
#include <stdio.h>
#include <stdlib.h>
typedef struct
{
    struct
    {   
        unsigned member1;
        unsigned  member2; 
    } str1;

    struct
    {
        unsigned member3;
        unsigned  member4; 
    } str2;

    struct
    {
        unsigned member5;
        unsigned  member6; 
    } str3;
} CONFIG_T;



/* 
file1.c
*/
CONFIG_T  cfg =
{
    .str1 = { 0x01, 0x02 },
    .str2 = { 0x03, 0x04 },
    .str3 = { 0x05, 0x06 }
};

Compiled with std C++11 and i get below error. Why the '.' has been used in code while assigning values ?

home $$  g++ -c -std=gnu++0x  initialze_list.cpp

initialze_list.cpp:34: error: expected primary-expression before ‘.’ token

initialze_list.cpp:35: error: expected primary-expression before ‘.’ token

initialze_list.cpp:36: error: expected primary-expression before ‘.’ token

I was not able to understand the reason for error. Please help.

Answer 1

What you posted is C code, not C++ code (note the .c file extention). However, the following code:

CONFIG_T  cfg =
{
    { 0x01, 0x02 },
    { 0x03, 0x04 },
    { 0x05, 0x06 }
};

should work fine.

You can also read about C++11 initialize lists in the wiki.

Answer 2

Designated aggregate initializers is a C99 feature, i.e. it is a feature of C language. It is not present in C++.

If you insist on compiling it as C++, you'll have to rewrite the initialization of cfg.