TrimString

#include <stdio.h>
#include <iostream>
#include <fstream>
#include <string>
using namespace std;


//字符串转大写
void stringToHight(string& strTxt)
{
	for (int i = 0; i < strTxt.length(); i++)
	{
		if (strTxt.at(i) >= 0x61 && strTxt.at(i) <= 0x7A)
		{
			strTxt.at(i) -= 0x20;
		}
	}
}

//字符串转小写
void stringToLower(string& strTxt)
{
	for (int i = 0; i < strTxt.length(); i++)
	{
		if (strTxt.at(i) >= 65 && strTxt.at(i) <= 90)
		{
			strTxt.at(i) += 0x20;
		}
	}
}

string StringConvert(const string &strSource, bool Islower)
{
	int32_t i, len;
	string str;

	len = strSource.length();
	if (Islower)
	{
		for (i = 0; i < len; i++)
		{
			if (strSource.at(i) == 0x20)
				continue;
			if (strSource.at(i) >= 0x41 && strSource.at(i) <= 0x5A) //A-Z
				str += strSource.at(i) + 0x20;
			else
				str += strSource.at(i);
		}
	}
	else
	{
		for (i = 0; i < len; i++)
		{
			if (strSource.at(i) == 0x20)
				continue;
			if (strSource.at(i) >= 0x61 && strSource.at(i) <= 0x7A) //a-z
				str += strSource.at(i) - 0x20;
			else
				str += strSource.at(i);
		}
	}

	return str;
}

//add hyb 修剪字符串
string TestStr(string& str)
{
	int nPos = 0;
	nPos = str.find_first_not_of(" ");
	if (str.at(nPos) != string::npos)
	{
		str = str.substr(nPos, str.length() - nPos);
	}

	nPos = str.find_last_not_of("");
	if (str.at(nPos) != string::npos)
	{
		str = str.substr(0, nPos + 1);
	}
	return str;
}

//实现String连接
string MyStrcat(string& str1, string& str2)
{
	string st = { '\0' };
	st = str1 + str2;
	return st;
}

//实现String复制
string MyStrcpy(string& str1, string& str2)
{
	string st = { '\0' };
	str1 = str2;
	return str1;
}

//实现String比较
int MyStrcmp(char* str1, char* str2)
{
	int i = 0;
	while ('\0' != *(str1 + i) && '\0' != *(str2 + i) && *(str1 + i) == *(str2 + i))
	{
		i++;
	}
	return *(str1 + i) - *(str2 + i);
}

int main(void)
{
  string num1 = "    hello WORLD";
	string num2 = "    HELLO world";
	stringToHight(num1);
	stringToLower(num2);
	TestStr(num1);
	TestStr(num2);
	cout << "num1: " << num1 << endl;
	cout << "num2: " << num2 << endl;

	string str1 = "hello";
	string str2 = "world";
	string str3 = "one";
	string str4 = "two";
	char ch1[20] = {0};
	char ch2[20] = { 0};
	printf("输入第一个字符串: ");
	fgets(ch1, 20, stdin);		//回车也会读进去
	printf("输入第二个字符串: ");
	fgets(ch2, 20, stdin);
	cout << "MyStrcat(str1, str2): " << MyStrcat(str1, str2) << endl;
	cout << "MyStrcpy(str3, str4): " << MyStrcpy(str3, str4) << endl;
	cout << "MyStrcmp(ch1,ch2): " << MyStrcmp(ch1, ch2) << endl;
}