// variable declarations // statements return 0;

scanf("%d", &x); // read printf("Value: %d", x); // print Arithmetic: +, -, *, /, % Relational: ==, !=, <, >, <=, >= Logical: && (AND), || (OR), ! (NOT) Assignment: =, +=, -=, etc. Increment/Decrement: ++, -- (prefix/postfix)

#include <stdio.h> // preprocessor directive int main() // main function

for loop: for(init; condition; update) while loop: while(condition) do-while loop: do while(condition); → executes at least once.

if (condition) // code; else if (cond2) // code; else // code;

Source code (.c) → Preprocessor → Compiler → Object code → Linker → Executable (.exe)

Machine (1GL) → Assembly (2GL) → High-level (3GL: C, Python) → 4GL, 5GL.

char str[] = "Hello"; // null terminated: 'H','e','l','l','o','\0' strlen() , strcpy() , strcat() , strcmp() , strchr() 11. Structures & Unions Structure: groups different data types.

struct Student int roll; char name[20]; float marks; ; struct Student s1 = 1, "John", 85.5; same memory shared among members (size = largest member). 12. File Handling Basic operations: Open, Read, Write, Close.

switch(expression) case 1: ... break; case 2: ... break; default: ... break;

return_type function_name(parameters) // body return value;