Premature optimization is the root of all evil.
On the other hand, we cannot ignore efficiency.
Desk calculator example — input — command line arguments — expression summary — logical and relational operators — increment and decrement — free store — explicit type conversion — statement summary — declarations — selection statements — declarations in conditions — iteration statements — the infamous goto — comments and indentation — advice — exercises.
Statements and expressions are introduced by presenting a desk calculator program that provides the four standard arithmetic operations as infix operators on floating-point numbers. The user can also define variables. ...