read single byte from socket ethernet

vishbynature

Hello,
i have been testing ethernet communication for a while, succesfully tested communication between Rpi and PC. Now i want to read single byte from PC to RPI i have used "write()", "putChar()" to send and "read()", "readAll()" to receive. now i want to receive single byte from PC. with read() you can only store incoming data in QString ,also used "getChar()" which is a boolean function. is there a way to receive single byte?

jsulm

@vishbynature said in read single byte from socket ethernet:

with read() you can only store incoming data in QString

Wrong. See https://doc.qt.io/qt-5/qiodevice.html#read-1 and other overloads.
There is nothing with QString.
But you did no tell us what you really mean: are you talking about QTcpSocket?

""getChar()" which is a boolean function" - and what is the problem?
From the documentation:
"Reads one character from the device and stores it in c. If c is 0, the character is discarded. Returns true on success; otherwise returns false."
https://doc.qt.io/qt-5/qiodevice.html#getChar

vishbynature

@jsulm
Ok I checked the first doc. i understand it well also i tagged QTcpSocket because all his functions(read,write,putChar,getChar) belong to that class.

"Reads one character from the device and stores it in c. If c is 0, the character is discarded. Returns true on success; otherwise returns false."
yes i wanted to get c from it.

ok when i said "read single byte from socket"
i want to send...... say 121 in a single byte
but when i receive it as 'y'
ascii for 'y' is 121.

i use "putChar(121)" in my Qt code in PC to send over ethernet and receive on my Rpi by "read(1)" as 'y'

i want to receive it as 121. is this possible?

jsulm

@vishbynature said in read single byte from socket ethernet:

but when i receive it as 'y'
ascii for 'y' is 121.

y IS 121 - so it's the same, 121 when interpreted as char is y. So, it works already.

char ch = 'y'; // Now ch contains number 121
std::cout << ch; // Will output y
std::cout << static_cast<int>(y); // will output 121

vishbynature

@jsulm
thanks for help.
now in my program i declare global variable say 'var'.
and using "socket->getChar(&var);"
i get the byte in var.
when i print it like
ui->textBrowser->append(QString::number(var));
i get the value.
was easy but had to work around it.

aha_1980

@vishbynature

now in my program i declare global variable say 'var'.

You don't need a global variable for that.

ui->textBrowser->append(QString::number(var));
i get the value.
was easy but had to work around it.

That's no workaround, that's just how computers work. Every byte has a value, and you can interpret is as ASCII code, that's what happens if you store the byte in a char and print it. What you wanted to do, is to print the numeric value of the byte, hence you need to convert it with QString::number()

Regards

vishbynature

@aha_1980
ok, thanks help again.
regards.