Quiz 5 IPC

Arrays

• A data structure consisting of an ordered set of elements of common type, stored contiguously in memory.
• The simplest data structure in the C language.
• An array definition takes the form: type identifier [size];

Elements

• Each element has a unique index, starting from 0, and holds a single value.
• To refer to a specific element, use the array name followed by bracket notation around the element's index.
• Example: grade[0] to access the first element of the grade array.

Check Array Bounds

• C compilers do not check whether an element's index is within the bounds of its array.
• It is the programmer's responsibility to ensure that the code does not include index values that point to elements outside the memory allocated for an array.

Initialization

• An array can be initialized when it is defined, similar to initializing variables.
• Initialization takes the form: type identifier [size] = {values};
• Example: int grade[8] = {90, 80, 70, 60, 50, 40, 30, 20};
• If the initialization fills all elements in the array, the size of the array can be inferred from the initialization set, and it does not need to be specified.

Parallel Arrays

• A convenient way to store tabular information using two parallel arrays.
• One array holds the key, while the other holds values.
• The arrays are parallel because the elements at the same index hold data that are related to the same entity.

Character Strings

• A character string is a char array with a special property: a terminator element follows the last meaningful character in the string.
• The null terminator is identified by the escape sequence '\0' and has the value 0 on any host platform.
• The null terminator occupies the first position in the ASCII and EBCDIC collating sequences.
• The value of the index identifying the null terminator element is the number of meaningful characters in the string.

Coding Style

• A well-written program is easy to read and maintain, with a consistent coding style throughout.
• The Allman coding style is recommended for introductory programming courses.

Identifiers

• Identifiers should be self-descriptive, making it easy for the reader to understand their meaning.
• Avoid referring the reader to external documents for explanation, and instead embed the meaning in the name.
• Short names are easier to read, but avoid very short names that are unclear.
• Nouns describe objects, and verbs describe actions.
• Avoid notations like Hungarian notation that include the type in the identifier.

Layout

• Layout and arrangement affect comfort and accessibility in code.
• Poorly laid out code can frustrate and lead to misreading.
• Negative space can visually separate elements and draw attention to certain parts of the code.

Indentation

• Indentation helps define code block structures and clearly shows logic.
• Recommended indentation is a tab of 4 or 8 characters.
• Using tabs rather than spaces enables easy adjustment of indentation.
• Aligning subordinate case labels with the switch keyword can minimize indentation with switch constructs.

Line Length

• The practical limit on line length is 80 columns, including indentation.
• Lines longer than 80 columns can be difficult to read, and may truncate or wrap in hard copy printouts.
• Break long string literals into sub-string literals separated by whitespace.

Braces

• The Allman style places the opening brace on its own line, indented to the preceding statement, and the closing brace on its own line, aligned with the opening brace.
• Braces are unnecessary with single statements, but provide clarity and maintainability.

Spaces

• Add a single space after commas, semi-colons, keywords, and around operators, except between parentheses and identifiers or constants.
• Avoid trailing spaces at the end of a line, and use blank lines to distinguish between constructs.
• Use comments to describe what is done, rather than how it is done, and keep them brief.

Comments

• Comments should introduce or summarize what follows, and avoid decoration or cuteness.
• Identify units where they matter, and comment data at the variable's declaration.
• Preface every source file with a header comment that includes the file name, author, date, and description.

Magic Numbers

• Avoid magic numbers by identifying them with symbolic names and using those names throughout the code.
• Set their value in either of two ways: directly in the code or through a header file.

Unmodifiable Variables

• An unmodifiable variable takes the form const type identifier = value;.
• Use them to define constants, standard rates, or default values.

Macro Directive

• A macro directive takes the form #define SYMBOL value.
• It instructs the C compiler to substitute every occurrence of SYMBOL with value throughout the code.
• Terminate the directive with an end of line character immediately following the value.

Introduction to Testing and Debugging

• Testing and debugging are essential skills for software developers to refine throughout their career.
• Testing ensures that a program executes successfully for a well-defined range of values, but may still crash for values outside this range.
• Debugging locates errors that produce incorrect results.

Errors

• Errors are classified into two kinds: syntactic and semantic errors.
• Syntactic errors break the rules of the programming language.
• Semantic errors fail to implement the intent and meaning of the program designer.

Testing Techniques

Black Box Testing

• Black box testing is a data-driven technique that treats the program as a black box.
• It tests the program against specifications and is input-output driven.
• Equivalence classes are used to reduce the number of possibilities to be tested.

White Box Testing

• White box testing is a logic-driven technique that treats the program as a glass box.
• It tests each possible path through the code at least once.
• Flow graphs are used to model the sequences, selections, and iterations in the source code.

Debugging Techniques

IDE Debugging

• Integrated Development Environments (IDEs) support text editing, coding, compiling, testing, and debugging in a unified application.
• The IDE used in this course is Microsoft's Visual Studio.
• Build and execute C programs in Visual Studio by creating a new project, writing the code, and clicking the "Local Windows Debugger" button.

Command-Line Debugging

• The GNU debugger (gdb) is a command-line debugging tool that ships with the gcc compiler for Linux platforms.
• Compile the source code with the -g option to use gdb.
• Run gdb by entering gdb a.out and set breakpoints before running the program.

Walkthrough Table

• A walkthrough emulates the CPU stepping through the code and is used to understand the control flow and memory changes of a source code snippet.
• The walkthrough solution consists of a record of changes and a table of program variables.
• The table lists the identifiers, types, and values of the variables, and is a simplified representation of RAM throughout the program's lifetime.