C++中String类的常用接口函数总结

#include <iostream>
#include <string>
using namespace std;
int main()
{
	string s;//string()
	string s1("hello world");//string(const char* s)
	string s2(s1);//string(const string& s)
	cout << s << endl;
	cout << s1 << endl;
	cout << s2 << endl;
	return 0;
}

int main()
{
	string s1("hello world");
	cout << s1.size() <<endl;
	cout << s1.capacity() << endl;
	s1.resize(34,'y');// 将s1中有效字符个数增加到34个，多出位置用'y'进行填充
	s1.resize(13);
	cout << s1.size() << endl;
	cout << s1.capacity() << endl;
	cout << s1 << endl;
	s1.resize(3, 'y');
	cout << s1.size() << endl;
	cout << s1.capacity() << endl;
	cout << s1 << endl;
	return 0;
}

int main()
{
	string s1("hello world");
	string::iterator vit = s1.begin();
	while (vit != s1.end())
	{
		cout << *vit ;
		vit++;
	}
	cout << "  " << endl;
	string::reverse_iterator it = s1.rbegin();
	while (it != s1.rend())
	{
		cout << *it;
		it++;
	}
	return 0;
}

int main()
{
	string s1("hello world");
	for (auto tmp: s1)//tmp只是原数组拷贝 不改变原数就改成引用会改变
	{
		cout << ++tmp;
	}
	cout << " " << endl;
	for (auto& tmp : s1)
	{
		cout << ++tmp ;
	}
	return 0;
}

int main()
{
	string s1("hello world");
	s1.push_back('a');
	s1.append("asddfs");
	s1 += 'a';
	s1 += "sfasd";
	cout << s1;
	return 0;
}

int main()
{
	string s1("hello.world");
	int pos1 = s1.find('.');
	string s ("string.cpp");
	int pos = s.rfind('.');
	string s2("aahello.world");
	int pos = s2.find(s1);//查找字符串
	//返回下标
	string s1("hello.worl.d");
	int pos = s1.find('.',6 );
	//第一个参数是要找的字符、字符串，第二个参数是从下标n开始查找
	cout << pos;
	return 0;
	// npos是string里面的一个静态成员变量
	// static const size_t npos = -1;
	//如果未找到匹配项，则该函数返回string::npos。
}

int main()
{
	string s1("hello.world");
	int pos1 = s1.find('.');
	string s2("aahello.world");
	string s3( s1.substr(1, 5));
	cout << s3 << endl;
	//从下标pos ，截取n个
	return 0;
	//返回字符串对象
}

int main()
{
	string s1;
	getline(cin,s1);
	cout << s1 << endl;
	return 0;
}

#include <iostream>
#include <string>
using namespace std;
    int main()
    {
        string s ("race a car");
        reverse(s.begin(), s.end());
        cout << s << endl;
        return 0;
    }