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C Programming: Data Types, Memory & Strings

C Programming: Data Types, Memory & Strings




C Programming: Data Types, Memory & Strings




🔗 C and C++ Data Type Hierarchy



Data Type




Scalar

Function

void

Aggregate




Pointer

Arithmetic

Enumeration

Array

Structure

Variant




Floating-point

bool

Integer

enum

struct

union




float

double

char

short

int

long

signed

unsigned






Key Concepts:



Scalar Types: Single values (int, float, char, pointers)

Aggregate Types: Collections of data (arrays, structures, unions)

Function Types: Represent functions and their signatures

void Type: Represents absence of type or value

Type Qualifiers: const, volatile, restrict modify behavior









🏨 Memory Organization

Memory is byte-addressable - each byte has a unique address



Memory Layout Example:


0x1000
65 ('A')
char
1 byte



0x1001
66 ('B')
char
1 byte



0x1002
0x00
char
null terminator



0x1004
1234
int
4 bytes (typically)



0x1008
3.14159
float
4 bytes



0x100C
0x1000
char*
pointer to char (8 bytes on 64-bit)





Animate Data Flow


Memory Organization Test Points:


Each byte has a unique memory address

Addresses increase sequentially (0x1000, 0x1001, 0x1002...)

Different data types occupy different amounts of memory

Memory alignment affects where data is stored

Pointers store memory addresses as their values









📍 Byte Addressable Memory - Code Examples



// Basic pointer and address demonstration
#include <stdio.h>

int main() {
int n1 = 4, n2 = 8;
int *pt1 = &n1, *pt2 = &n2;
char c1 = 'A', c2 = 'B', c6;
char *pc1 = &c1, *pc2 = &c2, *pc3 = &c6;

// Print addresses and values
printf("c1 address = %p, c1 value = %c\n", pc1, *pc1);
printf("c2 address = %p, c2 value = %c\n", pc2, *pc2);
printf("n1 address = %p, n1 value = %d\n", pt1, *pt1);
printf("n2 address = %p, n2 value = %d\n", pt2, *pt2);

return 0;
}




// Pointer arithmetic and memory addresses
#include <stdio.h>

int main() {
int arr[] = {10, 20, 30, 40};
int *ptr = arr;

// Show how array elements are stored in consecutive memory
for(int i = 0; i < 4; i++) {
printf("arr[%d] = %d, address = %p\n",
i, *(ptr + i), (ptr + i));
}

// Show byte-level addressing
char *byte_ptr = (char*)ptr;
printf("\nByte-by-byte view of first integer:\n");
for(…