|
|
实现简单的忽略大小写的字符串的比较
#include <iostream>
#include <string>
#include <algorithm>
#include <utility>
#include <functional>
using std::pair;
using std::cin;
using std::cout;
using std::endl;
using std::string;
using std::not2;
using std::ptr_fun;
int ciCharCompare(char c1, char c2)
{
int lc1 = tolower(static_cast<unsigned char>(c1));
int lc2 = tolower(static_cast<unsigned char>(c2));
if (lc1 < lc2) {
return -1;
}
if (lc1 > lc2) {
return 1;
}
return 0;
}
int ciStringCompareImpl(const string &s1, const string &s2);
int ciStringCompare(const string& s1, const string& s2)
{
if (s1.size() <= s2.size()) {
return ciStringCompareImpl(s1, s2);
} else {
return -ciStringCompareImpl(s2, s1);
}
}
int ciStringCompareImpl(const string& s1, const string& s2)
{
typedef pair<string::const_iterator,
string::const_iterator> PSCI;
PSCI p = mismatch(s1.begin(), s1.end(), s2.begin(),
not2(ptr_fun(ciCharCompare)));
if (p.first == s1.end()) {
if (p.second == s2.end()) {
return 0;
} else {
return -1;
}
}
return ciCharCompare(*p.first, *p.second);
}
void PrintCompareResult(const string& s1, const string& s2)
{
if (ciStringCompare(s1, s2) > 0) {
cout << s1 << " > " << s2 << endl;
} else if (ciStringCompare(s1, s2) < 0) {
cout << s1 << " < " << s2 << endl;
} else {
cout << s1 << " = " << s2 << endl;
}
}
int main()
{
string test1("FreeDomi");
string test2("FReedOmi");
PrintCompareResult(test1, test2);
test1[6] = 'Z';
PrintCompareResult(test1, test2);
test2[6] = 'z';
PrintCompareResult(test1, test2);
return 0;
}
运行效果如下图
|