C++字符串常用API

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#include<iostream>
#include<string>
#include<cstdlib>

using namespace std;

int main(){
	string str = "Be yourself";
	
	//提取字符串, 从第三位开始, 长度为8 
	string sub_str = str.substr(3, 8);
	cout << "Substr:" << sub_str << endl;
	
	//在字符串末尾添加字符, 不能是字符串 
	str.push_back('!');
	cout << "Push_back:" << str << endl;
	
	//插入字符串
	string insert_str = "-->";
	str.insert(2, insert_str);
	cout << "Insert:" << str << endl;
	//从第二位开始插入字符串的一部分(第0位开始后的2个字符) 
	str.insert(2, insert_str, 0, 2);
	cout << "New_Insert:" << str << endl;
	
	//替换字符串, 替换从下标为2的位置开始, 长度为2的字符串 
	str.replace(2, 2, " ");
	cout << "Replace:" << str << endl;
	
	//删除字符串, 下标为2开始后的3个字符 
	str.erase(2, 4);
	cout << "Erase:" << str << endl;
	//str.begin(), str.end()返回的是迭代器 
	str.erase(str.begin() + 1, str.end() - 1);
	cout << "Erase:" << str << endl;
	
	str = "abcdefabc";
	//正向匹配 
	cout << "Find:" << str.find("abc") << endl;
	//逆向匹配 
	cout << "Rfind:" << str.rfind("abc") << endl;
	
	//拷贝从0开始的4个字符 
	string copy_str;
	copy_str.assign(str, 0, 4);
	cout << "Copy:" << copy_str << endl;
	
	//比较字符串, 大于返回1, 相等返回0, 小于返回-1 
	string cmp_str1 = "abc";
	string cmp_str2 = "abb";
	int cmp_result = cmp_str1.compare(cmp_str2);
	cout << "Compare:" << cmp_result << endl; 
	
	//把整数写入到字符数组中
	char num_to_char[5];
	sprintf(num_to_char, "%d", 2333);
	cout << "Num_to_char:" << num_to_char << endl;
	
	//string转化为int, 标准库<cstdlib> 
	string str_to = "1.314";
	int str_to_int_result = atoi(str_to.c_str());
	cout << "Str_to_int.c_str():" << str_to.c_str() << endl;
	cout << "Str_to_int_result:" << str_to_int_result << endl;
	//string转化为float
	double str_to_float_result = atof(str_to.c_str());
	cout << "Str_to_float_result:" << str_to_float_result << endl;
	
	//int转化为string, 语言标准需设置成C++11 
	int int_to_str = 20;
	cout << "To_String:" << to_string(int_to_str) << endl; 
}

运行结果：