string dissapearing problem using strcpy and strcat

/*Hey all.....I have a little problem.*/

/*I create a string and initialise it*/

char longstring[250];
strcpy(longstring, "host-");

/*I also have another string query[500] and later in the code I initialise that.....then I add to it using strcat*/

/*THEN, for some mystical reason.....longstring[250] has, ummm.....dissapeared.....(longstring == "").....funny, huh? especially seeing as it isn't mentioned in the code AT ALL inbetween the points when it's there and when it's not*/

/*one other thing I noticed is that while all this is going through a loop, after a while, (longstring == 0), then after another while, (longstring == 00)......???????*/

anyone have any idea what's going on??????

thanks,

Des.

ok, I figured it out........

char buffer[5],
char longstring[250];

buffer was being past a string representation of integers in most cases.....but in one it was being passed a double (from sprintf).....[5] was not big enough to hold , say, 100.000000 ......so it was passing the last few digits into the next string, longstring....which is why it was printing 0, then 00......etc.

thanks anyways