Unit 1 : Introduction to C for IT Students

 Prepared By : Mr. Uday Shah (HOD-IT) 

 Unit 1 : Introduction to C

1. Introduction

• Computer programming is the process of designing and building executable programs.
• It enables computers to perform specific tasks like calculations, data processing, or automation.
• Programming involves logic, syntax, and solving real-world problems.
• It includes writing source code in a specific programming language.
• A good understanding of the basics is crucial for becoming a successful programmer.
• Programming helps bring software applications and systems to life.

 

2. Various Computer Languages

• Computer languages are categorized as machine-level, assembly-level, and high-level languages.
• High-level languages include C, C++, Java, Python, etc., which are human-readable.
• Machine language consists of binary (0s and 1s) and is understood directly by computers.
• Assembly language uses mnemonics and is processor-specific.
• Each language has its own syntax and use-case depending on the application.
• High-level languages require compilers or interpreters for execution.

 

3. History & Overview

• The history of programming languages began with machine and assembly language in the 1940s and 50s.
• C language was developed by Dennis Ritchie at Bell Labs in 1972.
• It laid the foundation for many modern languages like C++, Java, and C#.
• C is procedural, efficient, and widely used in system-level programming.
• Understanding the evolution helps grasp how programming paradigms have changed.
• The overview provides a broad picture of language generations and their characteristics.

 

4. C Character Set

• The C character set includes alphabets (A-Z, a-z), digits (0-9), and special symbols.
• It also includes white spaces and control characters like newline \n.
• These characters form the building blocks of C programs.
• Identifiers, keywords, constants, and operators are created using this character set.
• Escape sequences like \t, \\, \" are also part of the character set.
• Understanding it is essential for writing syntactically correct code.

 

5. C Tokens

• Tokens are the smallest individual units in a C program.
• Examples include keywords, identifiers, constants, strings, operators, and punctuators.
• Tokens help the compiler understand the structure of the code.
• Each token has a specific meaning in the C language.
• Proper use of tokens ensures error-free program compilation.
• A program is made by combining these tokens logically.

 

6. Keywords

• Keywords are reserved words with special meaning in C (e.g., int, return, if, while).
• They cannot be used as variable or function names.
• Keywords define the structure and control flow of a C program.
• There are 32 keywords in standard C.
• Each keyword performs a specific task in programming.
• Proper use of keywords ensures clarity and accuracy in logic.

 

7. Constants

• Constants are fixed values that do not change during program execution.
• They can be of types like integer, float, character, or string constants.
• Defined using #define or the const keyword in C.
• Constants improve code readability and maintenance.
• Examples include const int MAX = 100; or #define PI 3.14.
• Use of constants helps prevent accidental changes to important values.

 

8. Strings

• A string is a sequence of characters ending with a null character \0.
• Strings are stored as arrays of characters in C.
• Example: "Hello" is stored as {'H', 'e', 'l', 'l', 'o', '\0'}.
• String manipulation is done using functions like strcpy, strlen, strcmp, etc.
• Strings are widely used in user input, file handling, and display.
• Understanding strings is essential for effective text processing.

 

9. Identifiers and Variables

• Identifiers are names used for variables, functions, arrays, etc.
• They must begin with a letter or underscore and can include digits.
• Variables are used to store data values during program execution.
• Each variable has a data type, such as int, float, char, etc.
• Good identifier naming improves code readability.
• Variables are declared and initialized before use.

 

10. Operators

• Operators are symbols that perform operations on operands (e.g., +, -, *, /).
• Categories include arithmetic, relational, logical, assignment, and bitwise operators.
• They help in performing calculations, comparisons, and logical operations.
• Each operator has a defined syntax and precedence.
• Combining operators allows building complex expressions.
• Understanding operator usage is key to writing logic.

 

11. Operator Precedence and Associativity

• Operator precedence determines the order of operations in an expression.
• For example, * and / have higher precedence than + and -.
• Associativity determines the direction of evaluation (left-to-right or right-to-left).
• Example: a + b * c evaluates b * c first due to higher precedence.
• Proper knowledge avoids logical and syntax errors.
• Parentheses () can be used to override precedence.

 

12. Data Types in C

• Data types define the type of data a variable can hold.
• Common data types include int, float, char, and double.
• Derived data types include arrays, pointers, structures, and unions.
• Data types determine memory usage and operations allowed.
• Using the correct data type enhances program efficiency.
• Type modifiers like long, short, signed, unsigned alter data size and range.

 

13. Type Casting & Type Conversion

• Type casting is converting one data type into another manually.
• Syntax: (data_type) variable; e.g., (float) a casts a to float.
• Type conversion is done automatically by the compiler in some cases.
• It helps in ensuring accurate calculations and assignments.
• Implicit type conversion may lead to loss of data or precision.
• Casting ensures that expressions are evaluated in the desired format.

 

14. Pre–Processors in C

• Pre-processors begin with # and are processed before compilation.
• Common directives include #include, #define, #ifdef, etc.
• #include is used to include header files.
• #define is used to define constants or macros.
• Pre-processors help manage code modularity and reuse.
• They do not end with a semicolon and are not part of the actual code logic.

 

15. Introduction of Logic

• Logic is the backbone of programming and problem-solving.
• It involves using conditions, loops, and statements to control flow.
• Logical operators like &&, ||, ! are used to build complex conditions.
• Logical thinking helps break down problems into smaller parts.
• Developing logic is essential to writing correct and optimized code.
• Logic enables decision-making and automation in programs.

 

16. Basics of Algorithm

• An algorithm is a step-by-step procedure to solve a problem.
• It is language-independent and focuses on logic.
• Algorithms have input, output, finite steps, and well-defined operations.
• Writing good algorithms helps in efficient coding.
• Common examples include searching, sorting, and arithmetic algorithms.
• Algorithms are often expressed using pseudocode or flowcharts.

 

17. Basics of Flow Chart

• A flowchart is a visual representation of an algorithm or process.
• It uses standard symbols like rectangles (process), diamonds (decisions), and arrows (flow).
• Flowcharts help in understanding and debugging logic visually.
• They are useful in planning before actual coding.
• Easy to understand for both technical and non-technical users.
• Flowcharts are often the first step in logic development.

 

18. Dry-Run and Its Use

• A dry-run involves manually tracing a program's execution on paper.
• It helps identify logic or syntax errors before actual execution.
• Dry-run includes checking variable values step-by-step.
• Useful in debugging and understanding how a program flows.
• Especially effective for beginners to visualize logic.
• It is part of the testing process before final execution.

 

19. Other Logic Development Techniques (Algorithm and Flowchart Based On Programming)

• Combine flowcharts and algorithms to design logic before coding.
• Use pseudocode to describe algorithms informally in human-readable steps.
• Modular approach: break the program into smaller functions/modules.
• Trace tables can be used to simulate logic execution step-by-step.
• Practice with small problems to improve logic-building skills.
• These techniques ensure efficient, error-free, and maintainable code.

:: Best of Luck ::