改数组长度

?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52

//改变数组长度     #include <iostream>     using namespace std;   // #ifndef CHANGELENGTH1D_H #define CHANGELENGTH1D_H   #include<stdexcept> #include<algorithm>   template<typename T> void changeLength1D(T *&a,int oldLength, int newLength) {     if(newLength < 0)         throw std::runtime_error("New length must be >=0");       T* temp = new T[newLength];     int number = std::min(oldLength, newLength);     //copy( from_vector.begin(), from_vector.end(), to_vector.begin())     std::copy(a, a+number, temp);     delete [] a;     a = temp; }   // #endif // CHANGELENGTH1D_H       int main() {     try{         double *a = new double[2];         a[0] = 11;         a[1] = 12;         changeLength1D(a,2,6);           for(int i=2;i<6;i++)             a[i]=i;           for(int i=0;i<6;i++)             cout << a[i] << endl;         return 0;     }catch(runtime_error err)     {         cout << err.what() << endl;         return 0;     } }