#pragma pack(1)

pragma_pack.cpp

#pragma pack(1)
struct s_t {		// sizeof s_t = 11
	char a;		// offset = 0, align = 1
	int b;		// offset = 1, align = 1
	short c;	// offset = 5, align = 1
	int d;		// offset = 7, align = 1
}S;

#pragma pack()
struct s_t {		// sizeof s_t = 11
	char a;		// offset = 0, align = 1
	int b;		// offset = 4, align = 4
	short c;	// offset = 8, align = 2
	int d;		// offset = 12, align = 4
}S;