C++大小字母的转换方式

#include<iostream>
using namespace std;
//大小写字母转换通过ASCⅡ码值进行改变，小写-大写=32；
int main()
{
    char c1 = 'a';
    char c2 = 'A';
    cout << c1 << "  " << c2 << endl;
    c1 = c1 - 32;//小写转换成大写
    c2 = c2 + 32;//大写转换成小写
    cout << c1 << "  " << c2 << endl;
}

#include <iostream>
using namespace std;
int main()
{
	char a[20];
	int i = 0;
	cout<<"请输入一串字符:\n";
	cin>>a;
	for(;a[i];i++)
	{
		if(a[i] >= 'a'&&a[i] <= 'z')
            a[i] -= 32;
		else if(a[i] >= 'A'&&a[i] <= 'Z')
            a[i] += 32;
	}
	for(i = 0;a[i];i++)
		cout<<a[i];
	cout<<endl;
	system("pause");
	return 0;
}

#include <iostream>
using namespace std;
void main(void)
{
    char i;
    cout<<"Input,'#'for an end: "<<endl;
    while(1)
    {
        cin >> i;
        if ((i>=65)&&(i<=90))
        {
            i=i+32;
            cout << i;
        }
        else if((i>=97)&&(i<=122))
        {
            i=i-32;
            cout << i;
        }
        else
            cout << (int)i;
        if(i=='#')
            break;
    }
}

#include <iostream>
using namespace std;
int main()
{
    cout<<(char)toupper(97)<<'\n';
    cout<<(char)toupper('a')<<'\n';
    cout<<(char)tolower(66)<<'\n';
    cout<<(char)tolower('B')<<'\n';
    return 0;
}

#include<iostream>
#include<string>
using namespace std;
int main(int argc, char* argv[])
{
    //声明字符数组
    char str[80],*p;
    int i;
    //转换字符串中的小写为大写
    cout<<"将字符串中的小写字母转换为大写"<<endl;
    cout<<"请输入原字符串："<<endl;
    cin>>str;
    p=strupr(str);
    cout<<"p:"<<p<<endl;
    cout<<"string:"<<str<<endl;
    cout<<"___________________"<<endl;
    //转换字符串中的大写为小写
    cout<<"将字符串中的大写字母转换为小写"<<endl;
    cout<<"请输入原字符串："<<endl;
    cin>>str;
    p=strlwr(str);
    cout<<"p:"<<p<<endl;
    cout<<"string:"<<str<<endl;
    cout<<"___________________"<<endl;
	system("pause");
	return 0;
}

#include<iostream>
#include<cctype>
#include<vector>
using namespace std;
int main()
{
    vector<char> vch;
    int n;
    char elem;
    cout<<"请输入大小写字符的个数：";
    cin>>n;
    cout<<"请输入"<<n<<"个大小写字符：";
    for(int i = 0;i<n;++i)
    {
        cin>>elem;
        vch.push_back(elem);
    }
    vector<char>::iterator it = vch.begin();
    for(it;it != vch.end();++it)
    {
        if(*it >= 'a'&&(*it) <='z')
            *it = toupper(*it);
        else if(*it >= 'A'&& (*it) <= 'Z')
            *it = tolower(*it);
    }
    cout<<"大小写转化之后的结果：";
    vector<char>::iterator itera = vch.begin();
    for(itera;itera != vch.end();++itera)
        cout<<*itera;
    cout<<endl;
    return 0;
}

#include<iostream>
#include<algorithm>
#include<string>
#include<cctype>
using namespace std;
int main()
{
    cout<<"请输入一个全部大写的字符串：";
    string str;
    cin>>str;
    ///转小写
    transform(str.begin(),str.end(),str.begin(),tolower);
    ///transform(wstr.begin(), wstr.end(), wstr.begin(), towlower);
    cout<<"转化为小写后为："<<str<<endl;
    ///转大写
    cout<<"请再输入一个全部小写的字符串：";
    string s;
    cin>>s;
    transform(s.begin(), s.end(), s.begin(), toupper);
    ///transform(wstr.begin(), wstr.end(), wstr.begin(), towupper);
    cout<<"转化为大写后为："<<s;
    wstring wstr =L"Abc";
    transform(wstr.begin(), wstr.end(), wstr.begin(), towupper);
    cout<<wstr;
    return 0;
}

#include <iostream>
#include <cstring>
#include <windows.h>
#include <cctype>
#include <algorithm>
using namespace std;
int wmain(int argc, WCHAR* argv[])
{
    char ch = 'a';
    ch = toupper(ch);
    cout<<ch<<endl;
    WCHAR wch = 'a';
    wch = towupper(wch);
    cout<<char(wch)<<endl;
    WCHAR wideStr[] = L"Abc";
    _wcslwr_s(wideStr, wcslen(wideStr) + 1);
    _wcsupr_s(wideStr, wcslen(wideStr) + 1);
    wstring wstr =L"Abc";
    transform(wstr.begin(), wstr.end(), wstr.begin(), towupper);
    return 0;
}

#include <iostream>
#include <cassert>
using namespace std;
char* convert(char *src)
{
    char *p = src;
    assert(p != NULL);
    while(*p)
    {
        if ('A' <= *p && *p < 'Z')
            *p |= 0x20;
        else if ('a' <= *p && *p < 'z')
            *p &= ~0x20;
        p++;
    }
    return src;
}
int main()
{
    char src;
    cin>>src;
    convert(&src);
    cout<<src;
    return 0;
}

#include <iostream>
#include <string>
#include <algorithm>    // transform
using namespace std;
int main()
{
   string str = "abcdADcdeFDde!@234";
   transform(str.begin(), str.end(), str.begin(), ::toupper);
   cout << str << endl;
   transform(str.begin(), str.end(), str.begin(), ::tolower);
   cout << str << endl;
   return 0;
}