C Programming: Data Types

• C is a general-purpose programming language known for its efficiency, flexibility, and portability
• C serves as a foundation for other languages and is used in system programming, application development, and embedded systems

Data Types in C

• Data types specify what type of data a variable can hold
• Common data types:
  • int: Integer numbers (e.g., -3, 0, 5)
  • float: Floating-point numbers (e.g., -2.5, 0.0, 3.14)
  • double: Double-precision floating-point numbers for higher accuracy
  • char: Single characters (e.g., 'a', 'Z', '7')
  • void: Absence of a type
• Each data type has a specific memory size and range of values
• The range and storage size of basic data types can be altered with modifiers like short, long, signed, and unsigned
  • short int: Reduces storage for integers
  • long int: Increases storage for integers
  • signed int: Stores positive and negative integers
  • unsigned int: Stores non-negative integers only

Variables

• Variables are named storage locations holding specific data types
• Declaration: Before use, variables must be declared with their data type and name, for example: int age;
• Initialization: Assigning an initial value upon declaration, for example: int age = 25;

Operators

• Operators are symbols that perform operations on variables and values
• Common operator types:
  • Arithmetic operators: Perform math operations (+, -, *, /, %)
  • Relational operators: Compare values (==, !=, >, =,
• Operator precedence determines evaluation order in expressions

If-Else Constructs

• if statements execute a code block only if a condition is true
  • Syntax:

    if (condition) {
        // Code to execute if the condition is true
    }
    

• else statements execute a code block if the if condition is false
  • Syntax:

    if (condition) {
        // Code to execute if the condition is true
    } else {
        // Code to execute if the condition is false
    }
    

• else if statements check multiple conditions in sequence
  • Syntax:

    if (condition1) {
        // Code to execute if condition1 is true
    } else if (condition2) {
        // Code to execute if condition2 is true
    } else {
        // Code to execute if all conditions are false
    }
    

• Nested if statements involve placing an if statement inside another

Loops

• Loops repeatedly execute a code block until a condition is met
• Types of loops in C:
  • for loop: Use when the number of iterations is known
    • Syntax:

      for (initialization; condition; increment/decrement) {
          // Code to be executed repeatedly
      }
      

  • while loop: Use when the number of iterations is unknown, continues as long as the condition is true
    • Syntax:

      while (condition) {
          // Code to be executed repeatedly
      }
      

  • do-while loop: Similar to while, but the code block executes at least once before checking the condition
    • Syntax:

      do {
          // Code to be executed repeatedly
      } while (condition);
      

• Loop control statements:
  • break: Terminates the loop and transfers control outside the loop
  • continue: Skips the current iteration and proceeds to the next
• Nested loops: Placing one loop inside another

Arrays

• Arrays are collections of the same data type stored in contiguous memory
• Declaration: Specify the data type, name, and size, for example: int numbers;
• Initialization: Assign values to array elements, for example: int numbers = {1, 2, 3, 4, 5};
• Accessing elements: Accessed via their index (position), starting from 0, for example: numbers
• Multidimensional arrays: Arrays with more than one dimension (e.g., 2D arrays for matrices)

Functions

• Functions are self-contained code blocks for specific tasks
• Declaration: Specify the return type, function name, and parameters
  • Syntax: return_type function_name(parameter_list);
• Definition: Provide the code the function executes
  • Syntax:

    return_type function_name(parameter_list) {
        // Function body
        return value; // If the function returns a value
    }
    

• Calling a function: Execute a function by using its name with arguments
  • Example: int result = add(5, 3);
• Types of functions:
  • Built-in functions: From the C standard library (e.g., printf, scanf, sqrt)
  • User-defined functions: Created by the programmer
• Function arguments: Values passed when the function is called
• Return value: Value returned after execution
• Recursion: A function calling itself

Pointers

• Pointers store the memory address of another variable
• Declaration: Specify the data type of the variable the pointer points to, followed by an asterisk (*)
  • Example: int *ptr;
• Initialization: Assign the address of a variable using the & operator
  • Example: int num = 10; int *ptr = #
• Dereferencing: Access the value at the memory address using the * operator
  • Example: printf("%d", *ptr);
• Pointer arithmetic: Perform operations on pointers to move them in memory
• Pointers and arrays: Array names are constant pointers to the first element
• Dynamic memory allocation: Use functions like malloc and calloc to allocate memory dynamically

Structures

• Structures are user-defined data types grouping variables
• Declaration: Use the struct keyword
  • Syntax:

    struct structure_name {
        data_type member1;
        data_type member2;
        //...
    };
    

• Creating structure variables: Declare variables of the structure type
  • Example: struct Person { char name; int age; }; struct Person person1;
• Accessing members: Use the dot operator (.)
  • Example: person1.age = 25;
• Pointers to structures: Use pointers to access members indirectly
  • Example: struct Person *ptr = &person1; printf("%s", ptr->name);