How to create a buffer for reading socket data in C

Question

Using C / C++ socket programming, and the "read(socket, buffer, BUFSIZE)" method. What exactly is the "buffer" I know that char and byte are the same thing, but does it matter how many elements the byte array has in it? Does the buffer need to be able to hold the entire message until the null character?

Answer 1

BUFSIZE should be equal to the size of your buffer in bytes. read() will stop reading when the buffer is full. Here is an example:

#define MY_BUFFER_SIZE 1024

char mybuffer[MY_BUFFER_SIZE];
int nBytes = read(sck, mybuffer, MY_BUFFER_SIZE);

Answer 2

As always, use sizeof when you have the chance. Using the built-in operator sizeof, you ask the compiler to compute the size of a variable, rather than specify it yourself. This reduces the risk of introducing bugs when the size of the actual variable is different from what you think.

So, instead of doing

#define BUFSIZE 1500
char buffer[BUFSIZE];
int n = read(sock, buffer, BUFSIZE);

you really should use

char buffer[1500];
int n = read(sock, buffer, sizeof buffer);

Notice how you don't need parenthesis around the argument to sizeof, unless the argument is the name of a type.