寻找一种潜在的方法来比较两个不知道它是字符串还是任何其他类的值

Question

我正在寻找一种方法来实现我的代码，以便下面的泛型函数可以接受任何类型的变量，但是当它接受一个字符串时，它将使用下面的函数比较2个字符串，当它采用任何其他类型时变量，它将简单地使用正常的比较运算符。我试图使用函数重载来完成，如你所见：

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

#include "binaryTreeInterface.h" // Overloading the functions here FYI

using namespace std;

template <typename E>
class binarySearchTree: binaryTreeInterface<E>{
public:

int LessThan<E>(E itm1, E itm2) {
  if (itm1 < itm2) {return -1;}
  else if (itm1 > itm2) {return 1;}
  else if (itm1 == itm2) {return 0;}
}


int LessThan<string>(string s1, string s2) { 
  return strcmp(s1, s2);
}

void AddNode(E itm) {
    /* ... */
    if (LessThan(itm, v[i]) <= 0) {i = LeftChild(i);} // v[i] is a variable E 
    else if (LessThan(itm, v[i]) > 0) {i = RightChild(i);}
}

以下是我遇到的错误：

In file included from test_binarySearchTree.cpp:1:0:
binarySearchTree.h:26:9: error: expected ‘;’ at end of member declaration
     int Compare<E>(E itm1, E itm2) {
         ^

binarySearchTree.h:26:16: error: expected unqualified-id before ‘<’ token
     int Compare<E>(E itm1, E itm2) {
                ^

test_binarySearchTree.cpp:78:1: error: expected ‘}’ at end of input
 }
 ^

In file included from test_binarySearchTree.cpp:1:0:
binarySearchTree.h:24:5: error: expected unqualified-id at end of input
     }