百度网站联系方式,青浦网站建设,wordpress登录名,商标注册查询怎么查询std::string的resize()与reserve()的区别:
resize()#xff1a;改变的是size()与capacity()的大小
(1)、比原来的变小之后#xff0c;后面的会被截断
(2)、比原来的变大之后#xff0c;后面的会被填充新的东西#xff0c;不同的编译器可能会不同
reserve()#xff1a;…std::string的resize()与reserve()的区别:
resize()改变的是size()与capacity()的大小
(1)、比原来的变小之后后面的会被截断
(2)、比原来的变大之后后面的会被填充新的东西不同的编译器可能会不同
reserve()改变的只是capacity()的大小
程序如下
#include math.h
#include stdio.h
#include string
#includeiostreamusing namespace std;int main()
{std::string s1(hello);std::cout s1 s1 s1.size s1.size() s1.capacity s1.capacity() endl;std::cout after resize to 2 endl;s1.resize(2); //尺寸由5改变为2多余字符被截掉了,只剩下hestd::cout s1 s1 s1.size s1.size() s1.capacity s1.capacity() endl;std::cout after resize to 100 endl;s1.resize(100);//尺寸由2改变为100,后面的数据被填充了98个astd::cout s1 s1 s1.size s1.size() s1.capacity s1.capacity() endl;std::cout \n;std::cout endl;std::cout \n;std::string s2(hello);std::cout s2 s2 s2.size s2.size() s2.capacity s2.capacity() endl;std::cout after reserve to 20 endl;s2.reserve(20); //只改变capacity()的大小其他的不变std::cout s2 s2 s2.size s2.size() s2.capacity s2.capacity() endl;std::cout after reserve to 2 endl;s2.reserve(2); //只改变capacity()的大小其他的不变std::cout s2 s2 s2.size s2.size() s2.capacity s2.capacity() endl;return 0;
}
结果
