🔴 Advanced · Lesson 53

Standard Template Library (STL)

What is Standard Template Library (STL)?

Standard Template Library (STL)
STL is a powerful C++ library containing containers, iterators, algorithms and function objects. It helps write shorter and efficient programs.

Level
🔴 STL, Modern C++ and Projects

Example File
stl-introduction.cpp

Main Focus
Concept + syntax + practical C++ program

Why should you learn this?

It helps you write correct and readable C++ programs.
It is used repeatedly in school practicals, projects and competitive programming.
It builds the base for advanced topics such as OOP, STL and data structures.

Important Terms

Term	Meaning / Use
container	Standard Template Library (STL) programming में Container use होता है।
iterator	Standard Template Library (STL) programming में Iterator use होता है।
algorithm	Standard Template Library (STL) programming में Algorithm use होता है।
vector	Standard Template Library (STL) programming में Vector use होता है।
map	Standard Template Library (STL) programming में Map use होता है।

Syntax / Pattern

C++

Use containers like vector, set, map and algorithms like sort().

Example Program

main.cpp

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int main(){
    vector<int> v = {3,1,2};
    sort(v.begin(), v.end());
    for(int x : v) cout << x << " ";
}

Expected Output

1 2 3

Program Explanation

vector stores numbers.
sort() arranges them in ascending order.

Exam Tip: In C++ practical answers, write the logic first, then the program, then expected output. For theory, always include one suitable example.

Where will you use it?

competitive programming
data processing
fast development

Common Mistakes

Reinventing common data structures unnecessarily.
Using algorithm without including correct header.

Practice Tasks

List four STL containers.
Sort marks using vector.

Summary

Standard Template Library (STL) एक ज़रूरी C++ topic है। परिभाषा सीखें, syntax समझें, example program चलाएं और फिर practice tasks हल करके concept मज़बूत करें।