To read from a "TCP Communication" you are probably using read. The prototype for read is

ssize_t read(int fildes, void *buf, size_t nbyte);

and the return value is the number of bytes read (even if they are 0). So, let's say you're about to read 10 bytes, all of which are 0. You have an array with more than enough to hold all the data

int fildes;
char data[1000];
// fildes = TCPConnection
nbytes = read(fildes, data, 1000);

Now, by inspecting nbytes you know you have read 10 bytes. If you check data[0] through data[9] you will find they have 0;

Reference:

• Disadvantages of strlen() in Embedded Domain