Concatenate two char arrays?

Question

If I have two char arrays like so:

char one[200];
char two[200];

And I then want to make a third which concatenates these how could I do it?

I have tried:

char three[400];
strcpy(three, one);
strcat(three, two);

But this doesn't seem to work. It does if one and two are setup like this:

char *one = "data";
char *two = "more data";

Anyone got any idea how to fix this?

Thanks

Answer 1

If 'one' and 'two' does not contain a '\0' terminated string, then you can use this:

memcpy(tree, one, 200);
memcpy(&tree[200], two, 200);

This will copy all chars from both one and two disregarding string terminating char '\0'

Answer 2

strcpy expects the arrays to be terminated by '\0'. Strings are terminated by zero in C. Thats why the second approach works and first does not.

Answer 3

You can easily use sprintf

char one[200] = "data"; // first bit of data
char two[200] = "more data"; // second bit of data
char three[400]; // gets set in next line
sprintf(three, "%s %s", one, two); // this stores data