C++中求数组长度的方法详解

#include <iostream>
#include <string>
using namespace std;
template <class T>
int getArrSize(T& arr){
	return sizeof(arr) / sizeof(arr[0]);
}

template <class T>
int getArrLength(T& arr){
    return end(arr) - begin(arr);
}
int main(){
    string arr[] = {"a","b","c","e","f"};
    int arr2[] = {1,3,4,5};
    //string arr
    cout<<"sizeof(arr): "<<sizeof(arr)<<endl;
    cout<<"sizeof(arr[0]): "<<sizeof(arr[0])<<endl;
    cout<<"end(arr): "<<end(arr)<<endl;
    cout<<"begin(arr): "<<begin(arr)<<endl;
    cout<<"size of arr: "<<getArrSize(arr)<<endl;
    cout<<"length of arr:"<<getArrLength(arr)<<endl;

    //int arr
    cout<<"===================="<<endl;
    cout<<"sizeof(arr): "<<sizeof(arr2)<<endl;
    cout<<"sizeof(arr[0]): "<<sizeof(arr2[0])<<endl;
    cout<<"end(arr): "<<end(arr2)<<endl;
    cout<<"begin(arr): "<<begin(arr2)<<endl;
    cout<<"size of arr: "<<getArrSize(arr2)<<endl;
    cout<<"length of arr:"<<getArrLength(arr2)<<endl;
	return 0;
}