C Programming File I/O and Pointers

File Input and Output

• File Operations:
  • Opening: Use fopen(filename, mode).
  • Closing: Use fclose(file_pointer).
• Modes:
  • "r": Read
  • "w": Write (creates a new file or truncates existing)
  • "a": Append
  • "rb", "wb", "ab": Binary modes
• Reading/Writing:
  • fscanf(), fprintf() for formatted I/O.
  • fgets(), fputs() for string I/O.
  • fread(), fwrite() for binary data.

Pointers and Memory Management

• Pointers:
  • Store memory addresses of variables.
  • Declared using * (e.g., int *ptr;).
  • Dereferencing: Access value at address using *ptr.
• Dynamic Memory:
  • malloc(size): Allocates memory.
  • calloc(n, size): Allocates and initializes to zero.
  • realloc(ptr, new_size): Resizes allocated memory.
  • free(ptr): Deallocates memory.
• Pointer Arithmetic: Increment/decrement pointers to navigate through arrays.

Functions and Recursion

• Function Declaration: Specifies return type and parameters.
  • Example: int add(int a, int b);
• Function Definition: Contains the actual code.
• Recursion: Function calls itself.
  • Requires a base case to avoid infinite recursion.
  • Stack memory used for each function call.

Syntax and Data Types

• Basic Data Types:
  • int: Integer values
  • float: Floating-point numbers
  • double: Double precision floating-point
  • char: Single characters
• Type Modifiers:
  • short, long, unsigned: Modify basic types.
• Variable Declaration: data_type variable_name;

Control Structures

• Conditional Statements:
  • if, else if, else
  • switch: Multi-way branch.
• Loops:
  • for: Counter-controlled loop.
  • while: Condition-controlled loop.
  • do-while: Executes at least once.

Data Types

• Primitive Data Types: Basic types defined by C.
• Derived Data Types: Built from primitive types (arrays, pointers, structures, unions).

Array

• Definition: Fixed-size sequence of elements of the same type.
• Declaration: data_type array_name[size];
• Accessing Elements: Using indices (zero-based).
• Multidimensional Arrays: Arrays of arrays (e.g., int arr[3][4];).

Structures

• Definition: User-defined data type to group different data types.
• Declaration:
  • struct structure_name { data_type member1; data_type member2; };
• Accessing Members: Using the dot operator (e.g., struct_instance.member).
• Pointers to Structures: Use -> to access members via pointers.

These notes cover the key concepts of C programming across the specified subtopics, providing a clear and concise overview for study and review.

File Input and Output

• File Operations involve fopen to open files and fclose to close them.
• Modes for file operations include:
  • "r" for reading files.
  • "w" for writing, creating a new file or truncating an existing one.
  • "a" for appending data to the end of a file.
  • "rb", "wb", "ab" for binary file operations.
• For reading and writing in C:
  • fscanf() and fprintf() are used for formatted input and output.
  • fgets() and fputs() are for string input and output.
  • fread() and fwrite() handle binary data operations.

Pointers and Memory Management

• Pointers are variables that store memory addresses of other variables.
• Declaration involves using *, e.g., int *ptr;.
• Dereferencing a pointer accesses the value at the stored address using *ptr.
• Dynamic Memory Management functions include:
  • malloc(size) for allocating memory.
  • calloc(n, size) for allocating and zero-initializing memory.
  • realloc(ptr, new_size) for resizing previously allocated memory.
  • free(ptr) to deallocate memory.
• Pointer Arithmetic allows increments or decrements of pointers to navigate through arrays.

Functions and Recursion

• Function Declaration defines the return type and parameters, e.g., int add(int a, int b);.
• Function Definition contains the actual implementation of the function.
• Recursion is a technique where a function calls itself, requiring a base case to prevent infinite execution.
• Each function call uses stack memory for maintaining state.

Syntax and Data Types

• Basic Data Types include:
  • int for integers.
  • float for single-precision floating-point numbers.
  • double for double-precision floating-point numbers.
  • char for single character storage.
• Type Modifiers such as short, long, and unsigned adjust the storage characteristics of basic data types.
• Variable declaration follows the pattern: data_type variable_name;.

Control Structures

• Conditional Statements consist of:
  • if, else if, else for branching logic.
  • switch statement for multi-way branching based on value conditions.
• Loops allow repetitive execution of code:
  • for loops are counter-controlled.
  • while loops check a condition before execution.
  • do-while loops ensure at least one execution of the loop body regardless of the condition.

Data Types

• Primitive Data Types are fundamental types defined in C.
• Derived Data Types are constructed from primitive types, including arrays, pointers, structures, and unions.

Arrays

• Arrays are fixed-size sequences of elements, all of the same type.
• Declaration requires specifying the type and size: data_type array_name[size];.
• Elements are accessed using zero-based indices.
• Multidimensional Arrays are arrays of arrays, e.g., a two-dimensional integer array can be declared as int arr[][];.

Structures

• Structures are user-defined data types that group a variety of data types.
• Declaration follows the format:
  • struct structure_name { data_type member1; data_type member2; };.
• Structure members are accessed using the dot operator, e.g., struct_instance.member.
• Pointers to structures use the arrow operator (->) to access members, enabling easier manipulation of structure data.

Test your knowledge on file input/output operations, memory management, and pointers in C programming. This quiz covers essential functions and concepts that every C programmer should be familiar with, including modes of file access and dynamic memory allocation.