skipping bytes with memcpy

Projects Programming
1

How can i skip the first 7 bytes of "data" with using memcpy. im trying to use the first 7 bytes to verify the incoming data. but after i receive it i cannot use memcpy without trimming the first 7 bytes. heres the memcpy code i use,

memcpy(&st, data, sizeof(data));

how can i skip the first 7 bytes of data?

memcpy(&st, data, sizeof(data));

2

Perhaps this?

memcpy(&st, data + 7, sizeof(data)- 7);

Considering data is a pointer to the array

3

Power_Broker:
Perhaps this?

memcpy(&st, data + 7, sizeof(data)- 7);

that did work. see at first i tried

memcpy(&st, data + 7, sizeof(data)- 7);

but i didnt get the results i entirely expected. I'm transferring a struct between two esp8266. I want to add some verification do i came up with this,

sending struct,

struct sampleStruct {
  int var1 = 253;
  //byte Array[20];
  float var2 =5.5;
  unsigned long var3 = 999;
  unsigned long var4 =1;
  unsigned long var5=9999;
  unsigned long var6=7777;
  unsigned long var7=6666;
  unsigned long var8=5555;
 // bool var9;
};
sampleStruct st;

static os_timer_t intervalTimer;

static void replyToServer(void* arg) {
  AsyncClient* client = reinterpret_cast<AsyncClient*>(arg);
  // send reply
  if (client->space() > 32 && client->canSend()) {
   client->add("VERIFY",7);
   client->add((char *)&st, sizeof(sampleStruct));
    client->send();
    Serial.println("sent");
  }
}

i added " client->add("VERIFY",7);" hoping it would add that to the beginning 7 bytes of data that i can check for on the receiving side and verify the first 7 bytes. however only the first variable in the struct on the receiving side was populated the the right value. I change it slightly to this,

memcpy(&st, data +7, sizeof(sampleStruct));

Now i receive the whole struct fine. I'm hoping since the structs are identifical data types that i should be okay use sizeof(sampleStruct) as the size reference?

receiving struct,

static void handleData(void* arg, AsyncClient* client, void *data, size_t len) {
  Serial.printf("\n data received from client %s \n", client->remoteIP().toString().c_str());
  //  Serial.write((char *)data, len);
  memcpy(&st, data +7, sizeof(sampleStruct));
Serial.write((const char *)data);
Serial.println("");
  Serial.println(st.var1);
  Serial.println(st.var2);
   Serial.println(st.var3);
    Serial.println(st.var4);
     Serial.println(st.var5);
      Serial.println(st.var6);
       Serial.println(st.var7);
        Serial.println(st.var8);
        //Serial.println(st.var9);
}

the result in the serial console is,

 data received from client 192.168.4.2 
VERIFY
253
5.50
999
1
9999
7777
6666
5555