The Elements of a C++ Program

• Begin reading chapter 2.
  • This may or may not make sense but read it anyway.
  • Pay attention to terms.
    • Part of the class is to learn the vocabulary.
• In programming syntax is the set of formal rules governing how valid instructions are written in a programming language.
  • You have experience with English syntax.
  • Noun/verb agreement.
  • Spelling.
  • Punctuation.
• C++ (or any programming language) has a syntax as well.
  • A compiler is a program that translates a program from a high level language (like C++) to machine code.
  • In this process, the compiler checks for syntax errors
  • A syntax error is a message from the compiler that tells you where you have made a error in the language syntax.
  • We are generally given a line number and an attempt to identify the error.
  • You should fix syntax errors from the first (lowest line number) first.
• Semantics are the set of rules that determines the meaning of the instructions written in a programming language.
  • We can make sentences in English which are syntactically correct but are utter nonsense.
  • Or sentences which are ambiguous.
  • But it takes someone who understands meaning of the language to determine this.
  • The same is true with programming.
  • We only find semantic errors when we run our programs.
  • Or trace them by hand.
• You will spend quite a bit of time learning syntax at the beginning of your programming carrier.
• Syntax errors will dominate your programming time when you start.
• Later you will address semantic errors.
• A Reserved Word is a word that has special meaning in C++
  • We can not change the reserved words.
  • They are listed on page 985.
  • These are the words that make up the language
• An Identifier is a user defined name associated with a function or data object.
• We will use identifiers as we write program.
• An identifier must (These are syntax rules)
  • Start with a letter (A-Z,a-Z) or the underscore _
  • Must contain only letters, the underscore and digits (0-9)
  • Must not be a reserved word.
• As we program, we learn programming conventions
  • These are sometimes referred to as a style guide.
  • These are self imposed rules which make it easier to understand our programs.
  • Or perhaps imposed by employers, coordinators, teachers, ...
  • Google has a set.
  • As do many projects and companies (Just Google it)
  • As we learn different elements of C++, we will learn the associated conventions I would like you to employ.
• An operatoris a C++ symbol which performs an operation.
  • This includes math things (+,*,-,/)
  • Comparison things (<, >)
  • Logical things (and, or, not)
  • Other things too.
  • We will spend time learning what operators do.
  • A list of operators is on page 986.
• A data type is a specific set of data values, along with a set of operations on those values.
• We will study:
  • Integer
  • Character
  • Float
  • Boolean
  • String
  • Stream
• We need to know the data type so the compiler (computer really) can tell what we have stored in memory
  • Everything is really just stored as a collection of bits.
  • Based on the type of the data stored there, it is treated as one of the above data types.
• Programs manipulate data. To do so, we must declare a place to store that data.
  • A declaration is a statement which associates an identifier with a data object, function or data type so that the programmer can refer to the item by name.
  • This frequently associates a name and a data type with a location in memory.