memcpy was not declared error in eclipse CDT C++

I am trying to do memcpy

 char *pdata = data pointer;
 int64_t deviceId;
 memcpy(&deviceId, pdata+1, 8);
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And it complains "memcpy was not declared in this scope"

I have included below libraries in my header file

<stdio.h>
<stdlib.h>
<unistd.h>

How do I fix this problem. Thank in advance..

mempcy is defined in string.h, excerpt from man:

 SYNOPSIS
 #include <string.h>

 void *
 memcpy(void *restrict s1, const void *restrict s2, size_t n);

memcpy is in string.h , so add it

http://www.cplusplus.com/reference/clibrary/cstring/memcpy/