STL——string的赋值操作

功能：

1. 给string字符串进行赋值
2. string字符串拼接操作

赋值的函数原型：共有2种，分别为operate=和assign两种。

string& operator=(const char *s); //char*类型字符串 赋值给当前的字符串

string& operator=(const string *s); //把当前的字符串s赋值给当前的字符串

string& operator=(char c); //字符赋值给当前的字符串

string& assign(const char *s); //把字符串s赋给当前的字符串

string& assign(const char *s, int n); //把字符串的前n个字符赋值给当前字符串

string& assign(const string &s); //把字符串s赋给当前字符串

string& assign(int n, char c); //用n个字符c赋给当前字符串

使用小Demo:

#include<iostream>
#include<string>
using namespace std;
//string赋值操作
/*
string& operator=(const char *s); //char*类型字符串 赋值给当前的字符串
string& operator=(const string *s); //把当前的字符串s赋值给当前的字符串
string& operator=(char c); //字符赋值给当前的字符串
string& assign(const char *s); //把字符串s赋给当前的字符串
string& assign(const char *s, int n); //把字符串的前n个字符赋值给当前字符串
string& assign(const string &s); //把字符串s赋给当前字符串
string& assign(int n, char c); //用n个字符c赋给当前字符串
*/

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

	string str2;
	str2 = str1;
	cout << "str2=" << 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 << "str5=" << str5 << endl;

	string str7;
	str7.assign(7, 'w');
	cout << "str7=" << str7 << endl;
}

int main()
{
	test01();
	system("pause");
	return 0;
}

字符串拼接操作：

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

void test01()
{
	string str1 = "我";

	str1 += "爱学习";
	cout << "str1=" << str1 << endl;


	str1 += ':';
	cout << "str1=" << str1 << endl;

	string str2 = " 莎士比亚";
	str1 += str2;
	cout << "str1=" << str1 << endl;

	string str3 = "I";
	str3.append(" love");
	cout << "str3=" << str3 << endl;

	str3.append(" study abc", 6);//追加前6个字符
	cout << "str3=" << str3 << endl;

	str3.append(str2);
	cout << "str3=" << str3 << endl;

	str3.append(str2, 0,8); //参数2是从哪个位置进行截取，参数3是截取几个字符
	cout << "str3=" << str3 << endl;
}

int main()
{
	test01();
	system("pause");
	return 0;
}