[C++STL]string容器用法介绍

Posted 2021-06-27 Wecccccccc

string构造函数
代码如下:

#include <iostream>
#include <string>
using namespace std;

void test01()
{
	string s1;
	cout << "s1 = " << s1 << endl;

	const char *str = "hello world";
	string s2(str);
	cout << "s2 = " << s2 << endl;

	string s3(s2);
	cout << "s3 = " << s3 << endl;

	string s4(10, 'a');
	cout << "s4 = " << s4 << endl;

}

int main()
{
	test01();
	return 0;
}

测试结果:

总结:
string的多种构造方式没有可比性，灵活使用即可。

代码如下:

#include <iostream>
#include <string>
using namespace std;

void test01()
{
	string str1;
	str1 = "hello world";
	cout << "str1 = " << str1 << endl;

	string str2;
	str2 = str1;
	cout << str2 << endl;

	string str3;
	str3 = 'a';
	cout << "str3 = " << str3 << endl;

	string str4;
	str4.assign("hello c++");
	cout << "str4 = " << str4 << endl;

	string str5;
	str5.assign("hello c++", 5);
	cout << "str5 = " << str5 << endl;

	string str6;
	str6.assign(str5);
	cout << "str6 = " << str6 << endl;



}

int main()
{
	test01();
	return 0;
}

测试结果:

总结:
string的赋值方式很多，operator= 这种方式是比较实用的。

代码如下:

#include <iostream>
#include <string>
using namespace std;

void test01()
{
	string str1 = "我";

	str1 += "爱玩游戏";

	cout << "str1 = " << str1 << endl;

	str1 += ":";

	cout << "str1 = " << str1 << endl;

	string str2 = "LoL DNF";

	str1 += str2;

	cout << "str1 = " << str1 << endl;

	string str3 = "I";
	str3.append("Love");
	//str3.append(str2);
	str3.append("game abcde", 4);
	str3.append(str2, 4, 3);//从下标4位置开始，截取3个字符，拼接到字符串末尾
	cout << "str3 = " << str3 << endl;

}

int main()
{
	test01();
	return 0;
}

测试结果:

代码如下:

#include <iostream>
#include <string>
using namespace std;

void test01()
{
	//查找
	string str1 = "abcdefgde";

	int pos = str1.find("de");

	if (pos == -1)
	{
		cout << "no find" << endl;
	}
	else cout << "pos = " << pos << endl;

	pos = str1.rfind("de");

	cout << "pos = " << pos << endl;

}

void test02()
{
	//替换
	string str1 = "abcdefgde";
	str1.replace(1, 3, "1111");

	cout << "str1 = " << str1 << endl;
}

int main()
{
	test01();
	cout << "-----------------------------------"<<endl;
	test02();
	return 0;
}

测试结果:

总结:

代码如下:

#include <iostream>
#include <string>
using namespace std;

void test01()
{
	string s1 = "hello";
	string s2 = "aello";

	int ret = s1.compare(s2);

	if (ret == 0)
	{
		cout << "s1 = s2" << endl;
	}
	else if (ret > 0)
	{
		cout << "s1 > s2" << endl;
	}
	else
	{
		cout << "s1 < s2" << endl;
	}

}


int main()
{
	test01();
	
	return 0;
}

测试结果:

总结：
字符串对比主要是用于比较两个字符串是否相等，判断谁大谁小的意义并不是很大。

代码如下:

#include <iostream>
#include <string>
using namespace std;

void test01()
{
	string str = "hello world";

	for (int i = 0; i < str.size(); i++)
	{
		cout << str[i] << " ";
	}
	cout << endl;

	for (int i = 0; i < str.size(); i++)
	{
		cout << str.at(i) << " ";
	}
	cout << endl;


	//字符修改
	str[0] = 'x';
	str.at(1) = 'x';
	cout << str << endl;


}


int main()
{
	test01();
	
	return 0;
}

测试结果:

总结:
string字符串中单个字符存取有两种方式，利用[]或at

代码如下：

#include <iostream>
#include <string>
using namespace std;

void test01()
{
	string str = "hello";
	str.insert(1, "111");
	cout << str << endl;

	str.erase(1, 3);
	cout << str << endl;

}


int main()
{
	test01();
	
	return 0;
}

测试结果：

总结:
插入和删除的起始下标都是从0开始

代码如下:

#include <iostream>
#include <string>
using namespace std;

void test01()
{
	string str = "abcdefg";
	string subStr = str.substr(1, 3);
	cout << "subStr = " << subStr << endl;

	string email = "[e-mail]";
	int pos = email.find("@");
	string username = email.substr(0, pos);
	cout << "username = " << username << endl;
}


int main()
{
	test01();
	
	return 0;
}

测试结果: