c++ - 通用 keyCompare 方法

Question

请看下面的程序..

#include <stdio.h>
#include <malloc.h>
#include <iostream>
#include <string.h>

using namespace std;

int main()
{
    char *key1 = (char*)malloc(sizeof(char)*26);
    char *key2 = (char*)malloc(sizeof(char)*26);


    int intkey1 = 10;
    int intkey2 = 10;

    float floatkey1 = 13.5f;
    float floatkey2 = 13.5f;

    double doublekey1 = 18.5;
    double doublekey2 = 18.5;

    char charkey1[10] = "nikhil";
    char charkey2[10] = "nikhil";

    //cout<<sizeof(int)<<" "<<sizeof(float)<<" "<<sizeof(double)<<endl;

    memcpy(key1,&intkey1,sizeof(int));
    memcpy(key2,&intkey2,sizeof(int));

    int offset = sizeof(int);

    memcpy(&key1[offset],&floatkey1,sizeof(float));
    memcpy(&key2[offset],&floatkey2,sizeof(float));

    offset = offset + sizeof(float);

    memcpy(&key1[offset],&doublekey1,sizeof(double));
    memcpy(&key2[offset],&doublekey2,sizeof(double));

    offset = offset + sizeof(double);

    memcpy(&key1[offset],charkey1,sizeof(charkey1));
    memcpy(&key2[offset],charkey2,sizeof(charkey2));


    int diff = memcmp(key1,key2,26);
    if( diff > 0)
        cout<<"Key1 is greater than key2"<<endl;
    else if(diff < 0)
        cout<<"Key1 is smaller than key2"<<endl;
    else
        cout<<"Both keys are equal"<<endl;
}

我正在为数据库引擎开发一个 B+ 树，我需要一个通用的 keyCompare 方法...这种通过 memcpy 比较字节流的方法是否总是安全和万无一失的，或者我是否需要根据类型进行比较我从扫描数据库引擎中存在的列信息中获得的字符键中存在的字段？这是最快的吗？

Answer 1

Is this way of comparing byte streams by memcpy always the safe and foolproof

它不会在小端架构上使用整数和 float 生成正确的结果。而且它无法处理特殊的浮点值，如 inf 和 nan。

or should i need to compare based on the types of the fields present in char key that i get from scanning column information present in the database engine?

它应该使用特定于类型的方法来比较类型。对于涉及使用语言环境的字符串。