🔴 Advanced · Lesson 54

Vector in C++ STL

What is Vector in C++ STL?

Vector in C++ STL
A vector is a dynamic array that can grow or shrink at runtime. It supports fast indexing and easy insertion at the end.

Level
🔴 STL, Modern C++ and Projects

Example File
vector.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
vector	Vector in C++ STL programming में Vector use होता है।
push_back	Vector in C++ STL programming में Push_back use होता है।
size	Vector in C++ STL programming में Size use होता है।
index	Vector in C++ STL programming में Index use होता है।
dynamic array	Vector in C++ STL programming में Dynamic array use होता है।

Syntax / Pattern

C++

vector<int> v; v.push_back(value);

Example Program

main.cpp

#include <iostream>
#include <vector>
using namespace std;
int main(){
    vector<int> marks;
    marks.push_back(90);
    marks.push_back(85);
    cout << marks.size();
}

Expected Output

Program Explanation

push_back adds values at the end.
size() returns number of elements.

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?

marks list
dynamic records
algorithm practice

Common Mistakes

Accessing invalid index.
Using vector without #include <vector>.

Practice Tasks

Store five marks in vector and find total.
Remove last element using pop_back().

Summary

Vector in C++ STL एक ज़रूरी C++ topic है। परिभाषा सीखें, syntax समझें, example program चलाएं और फिर practice tasks हल करके concept मज़बूत करें।

Vector in C++ STL क्या है?

Vector in C++ STL
A vector is a dynamic array that can grow or shrink at runtime. It supports fast indexing and easy insertion at the end.

Level
🔴 STL, Modern C++ and Projects

Example File
vector.cpp

मुख्य फोकस
Concept + syntax + practical C++ program

इसे क्यों सीखें?

यह आपको सही और पढ़ने-योग्य C++ programs लिखने में मदद करता है।
यह school practicals, projects और competitive programming में बार-बार use होता है।
यह OOP, STL और data structures जैसे advanced topics की नींव बनाता है।

ज़रूरी Terms

Term	अर्थ / उपयोग
vector	Vector Vector in C++ STL programming में use होता है।
push_back	Push_back Vector in C++ STL programming में use होता है।
size	Size Vector in C++ STL programming में use होता है।
index	Index Vector in C++ STL programming में use होता है।
dynamic array	Dynamic array Vector in C++ STL programming में use होता है।

Syntax / Pattern

C++

vector<int> v; v.push_back(value);

Example Program

main.cpp

#include <iostream>
#include <vector>
using namespace std;
int main(){
    vector<int> marks;
    marks.push_back(90);
    marks.push_back(85);
    cout << marks.size();
}

Expected Output

Program Explanation

push_back adds values at the end.
size() returns number of elements.

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?

marks list
dynamic records
algorithm practice

आम गलतियाँ (Common Mistakes)

Accessing invalid index.
Using vector without #include <vector>.

अभ्यास (Practice Tasks)

Store five marks in vector and find total.
Remove last element using pop_back().

सारांश

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