What does this point in the structure code mean?

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int main(){
    char buff[129];
    WSADATA wsa;
    WSAStartup(MAKEWORD(2, 0), &wsa);

    struct sockaddr_in caddr;
    struct sockaddr_in saddr = {
        .sin_family      = AF_INET,
        .sin_addr.s_addr = htonl(INADDR_ANY),
        .sin_port        = htons(5000)
    };
}
c struct syntax

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1 answer

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In this context it is a way to indicate which members are to be used. It ends up serving to disambiguate whether that is a normal variable or a member of the structure. Without the point it could be just a variable. It’s an abbreviated form of writing like this:

struct sockaddr_in saddr = {
    saddr.sin_family      = AF_INET,
    saddr.sin_addr.s_addr = htonl(INADDR_ANY),
    saddr.sin_port        = htons(5000)
};

These names after the point are the members declared in the structure at some other point in the code, and what is before the point is the object.

Another way that works:

struct sockaddr_in saddr;
saddr.sin_family = AF_INET;
saddr.sin_addr.s_addr = htonl(INADDR_ANY);
saddr.sin_port = htons(5000);

I put in the Github for future reference.

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