As some of my teammate always complain that template-based code are really hard to understand and that they would prefer coding without, I will try here to explain how it works and propose some complexity-growing example.
NOTE1: that post will be periodically update....
NOTE2: that post/tutorial is design in a way to can do all exercise without local compiler, I wrote a solution using
Ideone, so create your account and write your own solution for all exercise.
A first look at the template syntax <> and their usage:
We using template and/or writing template you "can" meet the < CONTENT > syntax
Where Content can be:
- class T / typename T
- A data type, which maps to T
- An integral specification
- An integral constant/pointer/reference which maps to specification mentioned above.
1st Example
Imagine we want a function to multiply by 2 an integer
int mulByTwo(int v) { return v*2;}
And we can write
int I = mulByTwo(2);
Now we also want mulByTwo but for float and we avoid code duplication.
Question: Write only one function MulByTwo to deal with:
int I = mulByTwo(2);
double D = mulByTwo(2.0);
Solution:
here
Observe basic/simple "type deduction" error message
Now using the 1st example, what's happen if you call:
string S = mulByTwo("blahblah....");
Now build a function Sum, range-based to deal with iterator and pointer of any kind !
Tips: an iterator is just a simple base class implementing some operator like: ++,--,+=,-=,*, ->, [], etc...
Add the end with only 1 function, you should be able to execute:
int main() {
int testArray[5] = {0,1,2,3,4};
vector v = {0, 1, 2, 3, 4};
vector s = {"hello", " ", "world"};
cout << Sum(v.begin(), v.end()), cout << endl;
cout << Sum(testArray, testArray + sizeof(testArray)/sizeof(testArray[0])), cout << endl;
cout << Sum(s.begin(), s.end()), cout << endl;
return 0;
}
Solution:
here
How to use integral template
as for type deduction, the compiler will prepare everything at the compilation time.
Example:
template<int> struct example { static double value = N * 2.0; }
If we write:
cout << example<5>::value;
Exercise: Use that to compute factoriel<5> at compile time
Solution:
here.
------ > followings section are under construction <------------------------ br="">
Solving ambiguity / Explicit Template Arg Specification
Default template argument
Template and Specialization
