C Quick Reference:

The C Reference provides a bird's-eye view of the most important syntax, data types, and library functions. Use this as a guide for quick lookup when writing or debugging code.

1. Data Types and Sizes

While sizes vary by architecture, these are the standard sizes for modern 64-bit systems:

Type	Size	Format Specifier
`char`	1 Byte	%c
`int`	4 Bytes	%d
`float`	4 Bytes	%f
`double`	8 Bytes	%lf

2. Control Flow Syntax

Standard structures for decision making and loops:

// If-Else
if (condition) { ... } else if (cond2) { ... } else { ... }

// Switch Case
switch(var) {
case 1: ... break;
default: ...
}

// Loops
for (int i=0; i < n; i++) { ... }
while (condition) { ... }
do { ... } while (condition);

3. Pointer Reference

Pointers are variables that store memory addresses. They are the most powerful and dangerous part of C.

int *p; - Declaration of a pointer.
p = &x; - Address-of operator (Assigns address of x to p).
*p = 10; - Dereference operator (Accesses value at the address in p).
NULL - A pointer that points to nothing (safe to check).

4. Common Library Functions

Standard functions found in <stdio.h>, <stdlib.h>, and <string.h>:

Function	Purpose
`printf() / scanf()`	Output to screen / Input from keyboard.
`malloc() / free()`	Allocate / Deallocate memory on the heap.
`strlen()`	Find the length of a string (excluding \0).
`fopen() / fclose()`	Open and close a file stream.

5. Escape Sequences

Special characters used inside strings:

\n - Newline
\t - Tab
\\ - Backslash
\" - Double Quote
\0 - Null Terminator (End of string)

6. Operator Precedence

The order in which operators are evaluated (Top = Highest):

Parentheses: (), [], ->
Unary: ++, --, !, *, &
Arithmetic: *, /, % then +, -
Relational: <, >, ==, !=
Logical: && then ||
Assignment: =, +=, *= etc.

Pro Tip: When in doubt about precedence, use parentheses (). It makes your code clearer and prevents subtle bugs that are hard to find!