resize函数
语法:
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1.新元素数，元素值 void resize(size_type __new_size, const value_type& __x) 2.新元素数， void resize(size_type __new_size) |
resize() 改变Vector元素数量的大小
源代码
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/** * @brief Resizes the %vector to the specified number of elements. * @param new_size Number of elements the %vector should contain. * @param x Data with which new elements should be populated. * * This function will %resize the %vector to the specified * number of elements. If the number is smaller than the * %vector's current size the %vector is truncated, otherwise * the %vector is extended and new elements are populated with * given data. */ void resize(size_type __new_size, const value_type& __x) { if (__new_size < size()) erase(begin() + __new_size, end()); else insert(end(), __new_size - size(), __x); } /** * @brief Resizes the %vector to the specified number of elements. * @param new_size Number of elements the %vector should contain. * * This function will resize the %vector to the specified * number of elements. If the number is smaller than the * %vector's current size the %vector is truncated, otherwise * the %vector is extended and new elements are * default-constructed. */ void resize(size_type __new_size) { resize(__new_size, value_type()); } |
测试代码
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// 梁笔记 // https://zouzhongliang.com #include <iostream> #include <vector> using namespace std; int main() { vector<int> v1; vector<int> v2(3, 2); v1.push_back(1); v1.push_back(2); v1.push_back(3); v1.push_back(4); v1.push_back(5); cout<<"v1向量骨元素数："<<v1.size()<<endl; cout<<"v2向量骨元素数："<<v2.size()<<endl; //void resize(size_type __new_size) v1.resize(10); cout<<"v1向量骨元素数："<<v1.size()<<endl; //void resize(size_type __new_size, const value_type& __x) v1.resize(8, 6); cout<<"v1向量骨元素数："<<v1.size()<<endl; for(int i=0;i<v1.size();++i) cout<<v1[i]<<","; cout<<endl; } |
测试结果：
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v1向量骨元素数：5 v2向量骨元素数：3 v1向量骨元素数：10 v1向量骨元素数：8 1,2,3,4,5,0,0,0, |