How do I make a character array scanner properly?

Question

I start with this:

char delay_chars[10];

then I have a stream of incoming characters that I need to assign like this:

['I', ' ', 'l', 'o', 'v', 'e', ' ', 'p', 'i', 'e']

I can do that, but then more characters come in so I need it like this:

[' ', 'l', 'o', 'v', 'e', ' ', 'p', 'i', 'e', ' ']
['l', 'o', 'v', 'e', ' ', 'p', 'i', 'e', ' ', 'a']
['o', 'v', 'e', ' ', 'p', 'i', 'e', ' ', 'a', 'n']
['v', 'e', ' ', 'p', 'i', 'e', ' ', 'a', 'n', 'd']
['e', ' ', 'p', 'i', 'e', ' ', 'a', 'n', 'd', ' ']
[' ', 'p', 'i', 'e', ' ', 'a', 'n', 'd', ' ', 'c']
['p', 'i', 'e', ' ', 'a', 'n', 'd', ' ', 'c', 'a']
['i', 'e', ' ', 'a', 'n', 'd', ' ', 'c', 'a', 'k']
['e', ' ', 'a', 'n', 'd', ' ', 'c', 'a', 'k', 'e']

You get the idea. I don't know how I can remove the first character of a char array (like I do with a String, remove(0, 1)) and I don't know how to add a new element at the end.

If I had to guess, I'd make a loop that will reassign the index of each character one step back or something like that but I'm not sure if that's how I should do it.

• Delta_G: You can do it this way, but there's a better way that's faster and a lot less work. You want something called a circular buffer. Look that up and see if it doesn't do what you want differently but better.

Answer 1

If I had to guess, I'd make a loop that will reasign the index of each character one step back or something like that but I'm not sure if that's how I should do it.

Yep, that's pretty much it...

Here's how I do it:

char data[10];
if (Serial.available()) {
 char inch = Serial.read();
 for (int i = 0; i < 9; i++) {
 data[i] = data[i+1];
 }
 data[9] = inch;
}

Every incoming character gets added to the end of the array after everything else has been shuffled down one place.

• JingleBells: It's pretty frustrating that in C you have to do all array stuff yourself
• Majenko: There are functions that can do it for you, but it's not really worth using them for such a simple operation. The for loop could be done with memmove(data, data+1, 9);
• Majenko: @NovaliumCompany By the way, I just corrected a typo.
• JingleBells: Ok. I now have another annoying problem... my Arduino Uno seems to start to spit jibberish when I do some stuff... Do you mind helping me? (in a chatroom)
• Majenko: @NovaliumCompany Jibberish usually means you're overrunning a buffer. Maybe you're printing an array with no terminating NULL character?

Answer 2

You can use SerialTransfer.h to automatically packetize and parse your data for inter-Arduino communication without the headace. The library is installable through the Arduino IDE and includes many examples.

Here are the library's features:

This library:

• can be downloaded via the Arduino IDE's Libraries Manager (search "SerialTransfer.h")
• works with "software-serial" libraries
• is non blocking
• uses packet delimiters
• uses consistent overhead byte stuffing
• uses CRC-8 (Polynomial 0x9B with lookup table)
• allows the use of dynamically sized packets (packets can have payload lengths anywhere from 1 to 255 bytes)
• can transfer bytes, ints, floats, and even structs!!

Example TX Arduino Sketch:

#include "SerialTransfer.h"
SerialTransfer myTransfer;
void setup()
{
 Serial.begin(115200);
 Serial1.begin(115200);
 myTransfer.begin(Serial1);
}
void loop()
{
 myTransfer.txBuff[0] = 'h';
 myTransfer.txBuff[1] = 'i';
 myTransfer.txBuff[2] = '\n';
 myTransfer.sendData(3);
 delay(100);
}

Example RX Arduino Sketch:

#include "SerialTransfer.h"
SerialTransfer myTransfer;
void setup()
{
 Serial.begin(115200);
 Serial1.begin(115200);
 myTransfer.begin(Serial1);
}
void loop()
{
 if(myTransfer.available())
 {
 Serial.println("New Data");
 for(byte i = 0; i < myTransfer.bytesRead; i++)
 Serial.write(myTransfer.rxBuff[i]);
 Serial.println();
 }
 else if(myTransfer.status < 0)
 {
 Serial.print("ERROR: ");
 Serial.println(myTransfer.status);
 }
}

You can easily edit the above example code to transfer ['I', ' ', 'l', 'o', 'v', 'e', ' ', 'p', 'i', 'e'] instead of ['h', 'i', '\n'].