c# 截取字符串

string originalString = "Hello, World!";
string subString1 = originalString.Substring(7); // 结果: "World!"
string subString2 = originalString.Substring(7, 5); // 结果: "World"

string originalString = "Hello, World!";
string subString3 = originalString[7..]; // 结果: "World!"
string subString4 = originalString[7..12]; // 结果: "World"

string originalString = "Hello, World!";
int startIndex = 7;
int length = 10;

if (startIndex < originalString.Length && startIndex + length <= originalString.Length)
{
    string subString = originalString.Substring(startIndex, length);
    Console.WriteLine(subString);
}
else
{
    Console.WriteLine("索引越界");
}

string originalString = "";

if (!string.IsNullOrEmpty(originalString))
{
    string subString = originalString.Substring(0, 5);
    Console.WriteLine(subString);
}
else
{
    Console.WriteLine("字符串为空");
}