c# 学习笔记 – StringBuilder

本文介绍: c# 学习笔记 – StringBuilder

类结构
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StringBuilder官方参考文档：StringBuilder类

相关构造方法
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class Test {
    static void Main() {
        int capacity = 20; // 建议容量
        int maxCapacity = 2000;
        string? str = "hello, world";

        StringBuilder s1 = new StringBuilder(); // 默认起始容量为16
        StringBuilder s2 = new StringBuilder(capacity);
        StringBuilder s3 = new StringBuilder(str); // 若为null --> 空字符串, 默认起始容量为字符串长度
        StringBuilder s4 = new StringBuilder(capacity, maxCapacity); // 若capacity == 0 --> capacity自动转换为maxCapacity
        StringBuilder s5 = new StringBuilder(str, capacity); // 若 str 长度 大于capacity, 则初始capacity长度等于str的长度 
        StringBuilder s6 = new StringBuilder(capacity, maxCapacity);

        int startIndex = 1, length = str.Length - 1;
        StringBuilder s7 = new StringBuilder(str, startIndex, length, capacity);
    }
}

class Test {
    static void Main() {
        string str = "hello, world";
        
        StringBuilder sb = new StringBuilder(str);
        Console.WriteLine(sb.Capacity);
        Console.WriteLine(sb[0]);
        Console.WriteLine(sb.Length);
        Console.WriteLine(sb.MaxCapacity);
    }
}
/*
16
h
12
2147483647
*/

class Test {
    static void Main() {
        string str = "hello, world";
        StringBuilder sb = new StringBuilder(str);

        sb.Append("添加于同一行....");
        sb.AppendLine(",  我后面跟着一个行终止符哟......");
        sb.Append("我在新的一行啦......");
        Console.WriteLine(sb);

        // ? 可以用于可空类型的声明，添加到sb后面，此时即使sb == null, 也不会抛出异常，返回的StringBuilder会为 null 
        sb = null; 
        StringBuilder sb_tmp = sb?.AppendLine("");         
    }
}
/*
hello, world添加于同一行....,  我后面跟着一个行终止符哟......
我在新的一行啦......
*/