1, when executing a program C from the start of the present routine main, the main end.
2, C language provisions else is always paired with recently if in its previous unpaired.
3, the data stored in memory in the form of an int is complement.
4, once the defined array size is fixed, and must be the same type of array elements.
5, the array name passed as a parameter to the function, the first address to be treated as an array of arrays for the actual parameter name.
6, if the explicit description of the type of function is not added, the function of the implicit type as void.
7, unsigned and void reserved keywords in C.
8, three basic configurations: the order selection, cycle
9, getchar () function is a function of a character from the input terminal.
10, gets () function is a function of the input from the terminal a set of strings.
11, volatile role:
Variable declaration indicates that the variable may change at any time, associated with the variable operation, do not compile optimized to avoid making mistakes.
usefulness:
1) break variables for other programs to detect program changes, need to add volatile.
2) a multitasking environment among the tasks share mark, should be added volatile.
3) Memory-mapped registers also added volatile hardware description.