problem with comparing two string/chars in c++ - c++

Question

So i have created a java server and a c++ client.
The java server sends a message with a printwriter to the c++ client to execute a command (the data transfer is correct, no problems with that)
Im using a strcmp() to check if the string that client recieved with recv() is the string i want but when i try to check it, it doesn't work. I've tried to print out the line with the recieved buffer and i dont see any problems.
Here is the code that recieves and checks the buffer(c++, ignore some values becouse this is a small piece of the code)
char buffer[1024];
if (recv(s, buffer, sizeof(buffer), 0) == SOCKET_ERROR) {
cout << "Error CR#001" << endl;
return -1;
}
if (strcmp(buffer, "||clear") == 0) {
system("cls");
return 1;
}

Answer 1

In c++ you can use std::string for the buffer:
const ssize_t MAX_BYTES = 1024;
ssize_t noreceivedbytes;
std::string buffer;
buffer.reserve(MAX_BYTES + 1);
noreceivedbytes = recv(s, buffer.data(), MAX_BYTES, 0)
if (noreceivedbytes <= 0) {
cout << "Error CR#001" << endl;
return -1;
}
buffer.data()[noreceivedbytes] = '\0';
if (buffer == "||clear") {
system("cls");
return 1;
}
Safer c solution for completeness:
#define MAX_BYTES = 1024;
ssize_t noreceivedbytes;
chat buffer[MAX_BYTES];
noreceivedbytes = recv(s, buffer, MAX_BYTES - 1, 0)
if (noreceivedbytes <= 0) {
cout << "Error CR#001" << endl;
return -1;
}
buffer[noreceivedbytes] = '\0';
if (strcmp(buffer, "||clear") == 0) {
system("cls");
return 1;
}
Please note:
This answer brings you only over the top of the iceberg. There are many more things that could go wrong when dealing with sockets (as mentioned by others in comments).
recv() doesn't guarantee that the whole chunk of data sent from the server will be read completely. You could easily end up with partial strings like "||cle" or "||c".
The least thing you'll need to do is to receive the bytes from the socket in a loop, until you have something at hand you can reasonably parse and match.
The simplest way to do so is to define a very primitive protocol, which preceeds payload data sent with it's size (take care of endianess problems when converting the size sent as integer value from the received data).
Having that at hand, you'll know exactly how many bytes you have to read until you have the payload chunk completed, such it can be parsed and compared reasonably.
How to do all that in detail exactly would lead to far to be answered here. There are whole books written about the topic (I'd recommend Stevens, "Unix network programming").