size.c

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>

struct S1 {
	int64_t TradeId;
	int64_t ClientId;
	int VenueCode;
	int InstrumentCode;
	int64_t Price;
	int64_t Quantity;
	char Side;
};

struct S2 {
	int64_t TradeId;
	int64_t ClientId;
	int32_t VenueCode;
	int32_t InstrumentCode;
	int64_t Price;
	int64_t Quantity;
	char Side;
};

struct S3 {
	int64_t TradeId;
	int64_t ClientId;
	int32_t VenueCode;
	int32_t InstrumentCode;
	int64_t Price;
	int64_t Quantity;
};

int main(int argc, char const *argv[])
{
	struct S1 s1;
	printf("S1: %i\n", sizeof(s1));
	struct S2 s2;
	printf("S2: %ld\n", sizeof(s2));
	struct S3 s3;
	printf("S3: %ld\n", sizeof(s3));
	return 0;
}

size.go

package main

import (
	"fmt"
	"reflect"
)

type S1 struct {
	TradeId        int64
	ClientId       int64
	VenueCode      int
	InstrumentCode int
	Price          int64
	Quantity       int64
	Side           byte
}

type S2 struct {
	TradeId        int64
	ClientId       int64
	VenueCode      int32
	InstrumentCode int32
	Price          int64
	Quantity       int64
	Side           byte
}

type S3 struct {
	TradeId        int64
	ClientId       int64
	VenueCode      int32
	InstrumentCode int32
	Price          int64
	Quantity       int64
}

func main() {
	s1 := reflect.TypeOf(S1{}).Size()
	fmt.Printf("S1: %d\n\t%t\n", s1, S1{})
	s2 := reflect.TypeOf(S2{}).Size()
	fmt.Printf("S2: %d\n\t%t\n", s2, S2{})
	s3 := reflect.TypeOf(S3{}).Size()
	fmt.Printf("S3: %d\n\t%t\n", s3, S3{})
}