Common Bugs in C

1. ( n = 10) instead of ( n == 10)

2. Arrays start at [0]. The last valid element of
   char xline[10]
is xline[9], and it contains the null character \0

3. Confusing the value, address and contents of a variable:
x value of x
*x value of the cell pointed to by x
&x the address of x

Remember: the compiler will not catch [1] and [2], and it only catches [3] in function calls. The computer does what you say, not what you mean:

I really hate this darn machine;
I really wish they'd sell it;
It never will do what I want;
But only what I tell it.

Commonly Used ANSI Libraries

stdio.h Standard input/output
stdlib.h Assortment of functions, including random number generator and memory allocation
math.h mathematical functions
string.h string functions