Question

I’m not used to C as I’m primarily a Java guy, with some knowledge of C++, so forgive me if this is a trivial question. I could not seem to find an answer while searching online.

I’m initializing a char array…

char tcp[50];

So that I can concatenate a const char and a char. In examples I saw an easy way to do this was by creating that empty char array and then using…

strcat(x,y);

To stick them together.

Problem is, printing out the blank char array when it is set to “50” gives me a result of:

X??|? 

When I change it to…

char tcp[100];

And print it, its blank. Why is this?

Answer 1

The array contents are undefined, assuming it is a local (automatic) array.

Use:

char tcp[50] = "";

Or:

char tcp[50] = {0};

Or:

char tcp[50];
tcp[0] = 0;

Or:

char tcp[50];
memset(tcp, 0, sizeof(tcp));

As you like.