Lecture 2: expressions, assignment, control

• types
• assignment
• expressions
• control flow: if & while

types and declarations

• All variables have a type
• initialization <--> define

assignment

• lvalue = rvalue
• types must match
• rvalue may be a value or an expression or a function evaluation
• assignment returns a value (the lvalue)

expressions

• consists of primitives, operators, expressiosn
• expressions in Scheme -- precedence doesn't matter
• infix notation in C++ -- precedence matters
• operators: arithmetic, memory, increment, ternary
• *MUST* remember precedence rules
• nonmatching types is a COMPILER error

control flow

• if (bool) { code } else { code }
• else, else if (compare to cond)
• if in C and Scheme (value vs. control>
• if and ?: in C (control vs. value)