标签：reference cto int can gen 没有 bit clu enc
vector
http://www.cplusplus.com/reference/vector/vector/?kw=vector
template < class T, class Alloc = allocator<T> > class vector; // generic template
当你写个程序比如下面这个
#include <bits/stdc++.h> int main(){ int n; std::cin >> n; std::vector<int> v; for(int i = 0; i < n; i++) std::cin >> v[i]; for(int i = 0; i < n; i++) std::cout << v[i] << " "; return 0; }
你会发现欸， 程序怎么突然挂了 异常退出
那是因为上面的程序 vector 只是声明而已, 并没有开辟内存 你有如下两种选择
1) If you know the size of vector will be (in your case/example it‘s seems you know it):
#include <bits/stdc++.h> int main(){ int n; std::cin >> n; std::vector<int> v(n); for(int i = 0; i < n; i++) std::cin >> v[i]; for(int i = 0; i < n; i++) std::cout << v[i] << " "; return 0; }
2) if you don‘t and you can‘t get it in you‘r program flow then:
#include <bits/stdc++.h> int main(){ int n; std::cin >> n; std::vector<int> v; for(int i = 0; i < n; i++) { int x; std::cin >> x; v.push_back(x); }
for(int i = 0; i < n; i++) std::cout << v[i] << " "; return 0; }
标签：reference cto int can gen 没有 bit clu enc
原文地址：https://www.cnblogs.com/163467wyj/p/12008751.html
