Imagine running a grocery shop. You use different delivery boxes for apples, oranges, and eggs etc. But using a separate box for every item leads to complexity. Instead, one general-purpose box that can deliver any item is more efficient. Templates in C++ serve the same purpose: they allow writing a single piece of code that works for multiple data types.<\/p>\n\n\n\n
Templates enable generic programming, letting the compiler generate functions or classes for different data types automatically.<\/p>\n\n\n\n
Template help you write code that can automatically adjust to different data types, making your programs cleaner, shorter, and more efficient.<\/p>\n\n\n\n
A template in C++ is a generic blueprint that allows functions or classes\nto operate with different data types without rewriting the same code.\n<\/code><\/pre>\n\n\n\nIn code:<\/p>\n\n\n\n
template <typename T>\n<\/code><\/pre>\n\n\n\nThis introduces T<\/code> as a placeholder type.<\/p>\n\n\n\nFunction Templates<\/h2>\n\n\n\n
Function templates help avoid writing the same function multiple times for different data types.<\/p>\n\n\n\n
Example (Traditional Approach):<\/h3>\n\n\n\nint maxInt(int a, int b);\ndouble maxDouble(double a, double b);\n<\/code><\/pre>\n\n\n\nFunction Template:<\/h3>\n\n\n\ntemplate <typename T>\nT myMax(T a, T b) {\n return (a > b) ? a : b;\n}\n<\/code><\/pre>\n\n\n\nThe compiler automatically creates versions of this function based on the types used.<\/p>\n\n\n\n
Complete Example:<\/h3>\n\n\n\n#include <iostream>\nusing namespace std;\n\ntemplate <typename T>\nT add(T a, T b) {\n return a + b;\n}\n\nint main() {\n cout << add(3, 4) << endl;\n cout << add(2.5, 3.1) << endl;\n cout << add<string>(\"Hello \", \"World\") << endl;\n}\n<\/code><\/pre>\n\n\n\nClass Templates<\/h2>\n\n\n\n
Class templates generalize classes to store or operate on values of any type.<\/p>\n\n\n\n
Example Without Templates (Repetitive):<\/h3>\n\n\n\nclass IntBox { int value; };\nclass FloatBox { float value; };\n<\/code><\/pre>\n\n\n\nClass Template:<\/h3>\n\n\n\ntemplate <typename T>\nclass Box {\nprivate:\n T item;\npublic:\n void set(T value) { item = value; }\n T get() const { return item; }\n};\n<\/code><\/pre>\n\n\n\nUsage:<\/h3>\n\n\n\nBox<int> b1;\nb1.set(100);\n\nBox<string> b2;\nb2.set(\"Apples\");\n<\/code><\/pre>\n\n\n\nClass Template Example<\/h2>\n\n\n\n#include <iostream>\nusing namespace std;\n\ntemplate <class T>\nclass Calculator {\nprivate:\n T num1, num2;\npublic:\n Calculator(T a, T b) : num1(a), num2(b) {}\n T add() { return num1 + num2; }\n T subtract() { return num1 - num2; }\n};\n\nint main() {\n Calculator<int> obj1(10, 5);\n cout << obj1.add() << endl;\n\n Calculator<int> obj2(10.5, 2.2);\n cout << obj2.add() << endl;\n}\n<\/code><\/pre>\n\n\n\n6. Why Templates Matter<\/h2>\n\n\n\n\n- Reusable code<\/strong>: Write once, use for any type.<\/li>\n\n\n\n
- Type safety<\/strong>: Compiler handles type correctness.<\/li>\n\n\n\n
- Performance<\/strong>: Optimized code generated per type.<\/li>\n\n\n\n
- Foundation of STL<\/strong>: The Standard Template Library uses templates extensively.<\/li>\n<\/ul>\n\n\n\n
Introduction to STL (Standard Template Library)<\/h2>\n\n\n\n
To manage data efficiently in real-world applications, programmers need ready-made structures such as lists, maps, stacks, and sorting functions. Writing these from scratch every time is time\u2011consuming and error\u2011prone. The Standard Template Library (STL)<\/strong> provides these tools in a reusable and optimized form.<\/p>\n\n\n\nHere is the student\u2011friendly definition:<\/p>\n\n\n\n
STL (Standard Template Library) is a collection of template-based data structures,\nalgorithms, and iterators that allow efficient storage, processing, and traversal\nof data in C++.\n<\/code><\/pre>\n\n\n\nSTL provides the following major components:<\/p>\n\n\n\n
Containers:<\/h3>\n\n\n\n\nvector<T><\/code><\/li>\n\n\n\nlist<T><\/code><\/li>\n\n\n\nqueue<T><\/code><\/li>\n\n\n\nstack<T><\/code><\/li>\n\n\n\nmap<Key,Value><\/code><\/li>\n<\/ul>\n\n\n\nAlgorithms:<\/h3>\n\n\n\n\nsort()<\/code><\/li>\n\n\n\nfind()<\/code><\/li>\n\n\n\ncount()<\/code><\/li>\n<\/ul>\n\n\n\nIterators:<\/h3>\n\n\n\n
Generic pointers for containers.<\/p>\n\n\n\n
STL Example: vector<\/h2>\n\n\n\n#include <iostream>\n#include <vector>\nusing namespace std;\n\nint main() {\n vector<int> numbers;\n numbers.push_back(10);\n numbers.push_back(20);\n numbers.push_back(30);\n\n for (int x : numbers)\n cout << x << \" \";\n}\n<\/code><\/pre>\n\n\n\nSTL Example: pair<T1,T2><\/h2>\n\n\n\n#include <iostream>\n#include <utility>\nusing namespace std;\n\nint main() {\n pair<string, int> student;\n student.first = \"Ali\";\n student.second = 22;\n cout << student.first << \" is \" << student.second << \" years old.\";\n}\n<\/code><\/pre>\n\n\n\nSTL Algorithm Example: sort()<\/h2>\n\n\n\n#include <iostream>\n#include <vector>\n#include <algorithm>\nusing namespace std;\n\nint main() {\n vector<int> data = {4, 1, 9, 2};\n sort(data.begin(), data.end());\n\n for (int x : data)\n cout << x << \" \";\n}\n<\/code><\/pre>\n\n\n\nPractice Questions<\/h2>\n\n\n\n\n- Write a function template
minValue()<\/code>.<\/li>\n\n\n\n- Create a class template
Storage<T><\/code>.<\/li>\n\n\n\n- Create and print a vector of strings.<\/li>\n\n\n\n
- Sort a vector of doubles.<\/li>\n<\/ol>\n\n\n\n
<\/p>\n","protected":false},"excerpt":{"rendered":"
Imagine running a grocery shop. You use different delivery boxes for apples, oranges, and eggs etc. But using a separate box for every item leads to complexity. Instead, one general-purpose box that can deliver any item is more efficient. Templates in C++ serve the same purpose: they allow writing a single piece of code that works for multiple data types. Templates enable generic programming, letting the compiler generate functions or classes for different data types automatically. What Are Templates? Template…<\/p>\n