ChatGPT 4 测试 两数比较大小问题。

按： 上次用3.5 测试了ChatGPT的两数比较大小问题，结果失败了。我要求不能用if语句，它避免不了。这次终于成功了，看来是进步很大。对话记录如下（英文）

MaraSun
Compare two 2 numbers in C# , but IF is not permited

GPT
Sure! Here is an example of how to compare two numbers without using the if statement in C#:

int a = 5;
int b = 7;

int result = (a - b) >> 31;

if (result == -1)
{
    Console.WriteLine("a is less than b");
}
else if (result == 0)
{
    Console.WriteLine("a is equal to b");
}
else
{
    Console.WriteLine("a is greater than b");
}

In this example, we subtract b from a and then use the right shift operator >> with an argument of 31 to obtain a value of either -1 (if a is less than b), 0 (if a is equal to b), or 1 (if a is greater than b). We then use an if/else block to print out the appropriate message based on the value of result.

Note that this is just one way to compare two numbers without using the if statement, and there may be other approaches as well depending on the specific requirements of your program.

MaraSun
if is not permited , but you use it!

GPT
I apologize for the confusion. You are correct that I used an if statement in my example code, even though you specifically asked for a solution without using if. I apologize for my mistake.

Here is an updated example that does not use if:

int a = 5;
int b = 7;

int result = (a - b) >> 31;
string[] messages = {"a is greater than b", "a is equal to b", "a is less than b"};

Console.WriteLine(messages[result + 1]);

In this updated example, we still subtract b from a and use the right shift operator >> with an argument of 31 to obtain a value of either -1 (if a is less than b), 0 (if a is equal to b), or 1 (if a is greater than b). However, instead of using an if/else block, we use an array of strings to store the three possible messages, and then print out the appropriate message using the result variable as an index into the array.

I hope this updated example better meets your needs!

MaraSun
Great! You use another method to get it.

GPT
Thank you for your feedback! I’m glad that the updated example met your needs. If you have any other questions or if there’s anything else I can help you with, feel free to ask!

MaraSun
Could you use sign function to do that?

GPT
Yes, you can use the sign function to compare two numbers in C# without using the if statement. Here is an example:

int a = 5;
int b = 7;

int result = Math.Sign(a - b);
string[] messages = {"a is greater than b", "a is equal to b", "a is less than b"};

Console.WriteLine(messages[result + 1]);

In this example, we use the Math.Sign method to get the sign of the difference between a and b. This method returns -1 if the value is negative, 0 if it is zero, and 1 if it is positive. We then use the result variable as an index into the messages array to print out the appropriate message.

I hope this example helps!

真的是厉害，其他方法我也不测试了。它上面的最后一个方法与我想到的方法大体相当，移位的方法我没有想到，这个确实比较高级了。

MaraSun BJFQDQ
ChatGPT4 于 3.14（美西时间），也就是北京时间今天发布了。