How to Concatenate Two Byte Arrays in C?
I Am Coding on the Arduino Platform and I Am Trying to Write Something That Will Concatenate/Append Byte Arrays in C. Byte A[] = {A1, .. ., An}; Byte B[] =...
I am coding on the Arduino platform and I am trying to write something that will concatenate/append byte arrays in C.
byte a[] = {a1, ..., an};
byte b[] = {b1, ..., bm};
byte c[] = a + b; // equivalent to {a1, ..., an, b1, ..., bm}
What is the best way to get the above result?
I tried searching online, however I have not had much luck. I saw another answer on SO highlighting the steps needed in order to do this however I could not follow them. They also say that there are libraries that deal with this kind of thing, however as I am on Arduino I am unsure whether or not these are totally available to me.
I understand there needs to be some sort of memory manipulation in order for this to work however I am new to these kinds of low level manipulations so they do not make too much sense to me. I have experience in higher languages (C#, Java and some C++).
I should also add: Can the same technique work for:
byte a[] = {a1, ..., an};
byte b[] = {b1, ..., bm};
a = a + b
2 Answers
There is no byte type in C. Unless it's some type definition, you could use unsigned char or some fixed type from <stdint.h> portably. Anyway, here is some solution:
#include <stdio.h>
#include <string.h>
int main(void) {
unsigned char a[3+3] = {1, 2, 3}; // n+m
unsigned char b[3] = {4, 5, 6}; // m
memcpy(a+3, b, 3); // a+n is destination, b is source and third argument is m
for (int i = 0; i < 6; i++) {
printf("%d\n", a[i]);
}
return 0;
}
Make sure that array a has room for at least n + m elements (here n = 3 and m = 3 as well) in order to avoid issues with array overflow (i.e. undefined behavior, that may crash yor program or even worse).
If the sizes are known you can simply create a new byte array of that size and use simple loops to fill it.
Maya is a hardware enthusiast who tests and reviews smart home devices, smartphones, wearables, and audio gear. She focuses on practical consumer value and build quality.
