Function and Class Templates Lab

CSC-166 · Semester II · Object Oriented Programming

intermediate25 minAvailable

C++in-browser interpreter · runs locally

#include <iostream>
using namespace std;

int max2(int a, int b) { return (a > b) ? a : b; }
float max2(float a, float b) { return (a > b) ? a : b; }

int main() {
  cout << "max2(3, 7) = " << max2(3, 7) << endl;
  cout << "max2(2.5, 1.5) = " << max2(2.5f, 1.5f) << endl;
  return 0;
}

12 lines

Output

Write some code, then press Run. Stdout and errors appear here.

Lab brief

Objective

Write generic functions and a class template that work with int, double and string types.

Theory & concepts

A function template uses a type parameter T; the compiler instantiates a concrete function for each type used. A class template lets a whole class (like a Stack) work generically. Both keep one source of logic instead of duplicating code per type.

Rendering diagram…

Function and class templates with type parameter T

template <typename T>
T maxOf(T a, T b) { return (a > b) ? a : b; }

Stack<double> s;
s.push(1.5);
s.push(2.5);

Prerequisites

Lesson: Introduction to function templates
Lesson: Class templates

Instructions

1Write template function maxOf and test it with ints, doubles and chars.
2Write class template Stack<T> with push, pop and empty.
3Instantiate Stack<int> and Stack<string> and exercise both.
4Try maxOf(10, 2.5) and observe the deduction conflict error.
5Fix the call with an explicit type argument and re-run.

Tasks

Generic maxOf
Verify correct results for int, double and char arguments.
Generic stack
Push/pop three ints and three strings, checking LIFO order.
Mixed-type deduction
Explain the error for maxOf(10, 2.5) and resolve it explicitly.

Self-check

maxOf returns correct results for every tested type.
Stack<T> maintains LIFO order for int and string instantiations.
The student explains template instantiation and the mixed-type error.

Environment

editorstdout consolecompiler errorstest cases