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C++ Day 39

  C++ Day 39 STL Containers (Deep Understanding & Real Usage) Till now, you already know arrays, vectors, loops, and STL algorithms. Today, we go one step deeper and understand STL containers , which are the backbone of modern C++ programming. In real projects and competitive coding, choice of container matters a lot. 1. What are STL Containers? STL containers are data structures provided by C++ to store data efficiently. They handle: memory management resizing element access performance optimization You focus on logic , not memory handling. 2. Categories of STL Containers STL containers are mainly divided into: Sequence Containers Associative Containers Unordered Containers Container Adapters 3. Sequence Containers These store data in sequence . 3.1 Vector Most used container in C++. vector< int > v; Key Features: Dynamic size Contiguous memory Fast random access Slower insertion in middle Example: v. push_...
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C++ Day 9

 C ++ Day 9: Functions Deep Dive

🔹 1. Function overloading
Definition: Function overloading allows many functions with the same name but different parameters.

CPP
Copy
edit
#INCLUDE <iostream>
using namespace std;

Zero print (int I) {
Cout << "Printing into:" << I << Endl;
,

Zero print (double d) {
Cout << "Printing double:" << d << endl;
,

Zero print (string s) {
cout << "printing string:" << s << endl;
,

int main() {
Print (5);
Print (3.14);
Print ("hello");
Return 0;
,
🔹 2. Default argument
Definition: You can provide a default value for function criteria.

CPP
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edit
#INCLUDE <iostream>
using namespace std;

Zero greeting (string name = "guest") {
Cout << "Hello," << Name << "!" << Endl;
,

int main() {
Greetings ("Alice");
greet(); // Uses default
Return 0;
,
🔹 3. Recurrence
Definition: A function that calls itself.

Example: Factorial

CPP
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#INCLUDE <iostream>
using namespace std;

Int Factorial (Int N) {
If (n <= 1) returns 1;
Return N * Facterial (N - 1);
,

int main() {
Cout << is the factial of "5:" << Factorial (5) << Endl;
Return 0;
,
🔹 4. Inline functions
Definition: The compiler suggests the body of the function directly inserting to reduce overhead.

CPP
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edit
#INCLUDE <iostream>
using namespace std;

Inline Int Square (Int X) {
X * x return;
,

int main() {
Cout << is the class of 4: "<< class (4) << endl;
Return 0;
,
🔹 5. Static variable in functions
Definition: A stable variable inside a function retains its value between the call.

CPP
Copy
edit
#INCLUDE <iostream>
using namespace std;

Zero counter () {
Static int count = 0;
Counting ++;
Cout << "count:" << count << Endl;
,

int main() {
counter();
counter();
counter();
Return 0;
,
🧠 Practice
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