🔴 Advanced · Lesson 58

Iterators in STL

What is Iterators in STL?

Iterators in STL
Iterators act like pointers to traverse STL containers. They provide a common way to move through vectors, sets, maps and other containers.

Level
🔴 STL, Modern C++ and Projects

Example File
iterators.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
iterator	Iterators in STL programming में Iterator use होता है।
begin	Iterators in STL programming में Begin use होता है।
end	Iterators in STL programming में End use होता है।
dereference	Iterators in STL programming में Dereference use होता है।
traversal	Iterators in STL programming में Traversal use होता है।

Syntax / Pattern

C++

for(auto it = v.begin(); it != v.end(); ++it)

Example Program

main.cpp

#include <iostream>
#include <vector>
using namespace std;
int main(){
    vector<int> v = {5,10,15};
    for(auto it = v.begin(); it != v.end(); ++it)
        cout << *it << " ";
}

Expected Output

5 10 15

Program Explanation

begin() points to first element.
end() points after last element.
*it gives current value.

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?

STL traversal
algorithms
generic programming

Common Mistakes

Dereferencing end() iterator.
Modifying container while using invalidated iterator.

Practice Tasks

Traverse map using iterator.
Explain begin() and end().

Summary

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

Iterators in STL क्या है?

Iterators in STL
Iterators act like pointers to traverse STL containers. They provide a common way to move through vectors, sets, maps and other containers.

Level
🔴 STL, Modern C++ and Projects

Example File
iterators.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
iterator	Iterator Iterators in STL programming में use होता है।
begin	Begin Iterators in STL programming में use होता है।
end	End Iterators in STL programming में use होता है।
dereference	Dereference Iterators in STL programming में use होता है।
traversal	Traversal Iterators in STL programming में use होता है।

Syntax / Pattern

C++

for(auto it = v.begin(); it != v.end(); ++it)

Example Program

main.cpp

#include <iostream>
#include <vector>
using namespace std;
int main(){
    vector<int> v = {5,10,15};
    for(auto it = v.begin(); it != v.end(); ++it)
        cout << *it << " ";
}

Expected Output

5 10 15

Program Explanation

begin() points to first element.
end() points after last element.
*it gives current value.

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?

STL traversal
algorithms
generic programming

आम गलतियाँ (Common Mistakes)

Dereferencing end() iterator.
Modifying container while using invalidated iterator.

अभ्यास (Practice Tasks)

Traverse map using iterator.
Explain begin() and end().

सारांश

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