声明后在C ++向量中分配元素 [英] Allocating elements in C++ vector after declaration

问题描述

请参考下面的代码和注释:

Please refer to the code and comments below:

vector<int> v1(10);
cin>>v1[0]; // allowed
cin>>v1[1]; // allowed

// now I want v1 to hold 20 elements so the following is possible:

cin>>v1[15]>>v[19]; // how to resize the v1 so index 10 to 19 is available.

推荐答案

您只需要在添加新值之前重新调整向量大小即可:

You simply need to resize the vector before adding the new values:

v1.resize(20);

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