boost之string_algo

string_algo是用于处理字符串查找，替换，转换等一系列的字符串算法

前缀i:表示大小写不敏感

后缀_copy:表示不变动输入,返回处理结果的拷贝

后缀_if:表示算法需要一个判断式的谓词函数对象。

#include <iostream>
#include <vector>
#include <string>
#include <boost/algorithm/string.hpp>
using namespace std;
using namespace boost;

int main()
{
	string str("readme.txt");
	if (ends_with(str,"txt"))//判断后缀
	{
		cout << to_upper_copy(str) + " UPPER" <<endl;//大写
	}
	replace_first(str,"readme","followme");//替换
	cout << str <<endl;
	vector<char> v(str.begin(),str.end());
	vector<char> v2 = to_upper_copy(erase_first_copy(v,"txt"));
	for (int i = 0;i  < v2.size();++i)
	{
		cout << v2[i];
	}
	return 0;
}

1.大小写转换，如上。

2.判断式

2.1判断式(算法)，用于子串的匹配

starts_with

ends_with

contains

equals

lexicographcical_compare

#include <iostream>
#include <vector>
#include <string>
#include <boost/algorithm/string.hpp>
using namespace std;
using namespace boost;

int main()
{
	string str("Power Bomb");
	if (iends_with(str,"bomb"))
	{
		cout << "success iends_with" <<endl;
	}
	if (ends_with(str,"bomb"))
	{
		cout << "success ends_with" <<endl;
	}
	if (contains(str,"er"))
	{
		cout << "success contains" <<endl;
	}
	
	return 0;
}

 2.2.判断式（函数对象）用于字符串之间的比较

#include <iostream>
#include <vector>
#include <string>
#include <boost/algorithm/string.hpp>
using namespace std;
using namespace boost;

int main()
{
	string str1("Samus");
	string str2("samus");
	if (is_equal()(str1,str2))
	{
		cout << "is equal" <<endl;
	}
	if (is_less()(str1,str2))
	{
		cout << "is less" <<endl;
	}
	
	return 0;
}

 2.3.分类（返回函数对象）用于分类

is_space判断字符是否为空格

is_alnum判断是否为字符或者数字

3.修剪

trim_left,trim_right,trim删除左右两端的空格，使用谓词判断if

#include <iostream>
#include <vector>
#include <string>
#include <boost/format.hpp>
#include <boost/algorithm/string.hpp>
using namespace std;
using namespace boost;

int main()
{
	format fmt("%s
");
	string str = " samus aran";
	cout << fmt % trim_copy(str);
	cout << fmt % trim_left_copy(str);
	trim_right(str);
	cout << fmt % str;

	string str2 = "2013 Happy lin Year!";
	cout << fmt % trim_left_copy_if(str2,is_digit());
	cout << fmt % trim_right_copy_if(str2,is_punct());

	return 0;
}

4. 查找

find_first 查找字符串第一次出现的位置

find_last 查找字符串最后一次出现的位置

#include <iostream>
#include <vector>
#include <string>
#include <boost/format.hpp>
#include <boost/algorithm/string.hpp>
using namespace std;
using namespace boost;

int main()
{
	format fmt("%s
.pos=%d
");
	string str = "Long long ago,there was a king.";
	iterator_range<string::iterator> rge;
	rge = find_first(str,"long");
	cout << fmt %  rge % (rge.begin()-str.begin());
	

	return 0;
}

5.替换和删除与查找类似

#include <iostream>
#include <vector>
#include <string>
#include <boost/format.hpp>
#include <boost/algorithm/string.hpp>
using namespace std;
using namespace boost;

int main()
{
	string str = "Samus beat the monster.
";
	cout << replace_first_copy(str,"Samus","samus");
	replace_first(str,"beat","kill");
	cout <<str;

	return 0;
}

6.分割

#include <iostream>
#include <vector>
#include <string>
#include <deque>
#include <list>
#include <boost/format.hpp>
#include <boost/algorithm/string.hpp>
using namespace std;
using namespace boost;

int main()
{
	string str = "Smaus,Link.Zelda::Mario_Luigi+zelda";
	deque<string> d;
	ifind_all(d,str,"zELDA");
	if (d.size())
	{
		cout << "split right" <<endl;
	}
	list<string> l;
	split(l,str,is_any_of(",.:_+"));
	for (list<string>::iterator it = l.begin();it != l.end();++it)
	{
		cout << *it <<endl;
	}

	return 0;
}

 7.合并

#include <iostream>
#include <vector>
#include <string>

#include <boost/assign.hpp>
#include <boost/algorithm/string.hpp>
using namespace std;
using namespace boost;
using namespace boost::assign;

int main()
{
	vector<string> v = list_of("liuwei")("linlin")("ceshi");
	cout << join(v,"+")<<endl;
	struct is_contains_i
	{
		bool operator()(const string &x)
		{
			return contains(x,"i");
		}
	};
	cout << join_if(v,"****",is_contains_i());
	return 0;
}