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// MARK:
    // MARK: 演示
    /// 演示
    private func showHow() {
        
        let originalString = "ReLIFE重返17岁";
        
        // 从x开始到y结束
        let a = xnStringHaveRange(originalString,start: 7,end: 8);
        
        // 从前面开始 截取x个字符
        let c = xnStringHaveFront(originalString,length: 6);
        
        // 从后面开始 截取x个字符
        let b = xnStringHaveBack(originalString,length: 6);
        
        // 获取字符x 后面的字符串
        let d = xnStringHaveTargetBackStirng(originalString,targetSring: "E");
        
        // 获取字符x 前面的字符串
        let e = xnStringHaveTargetFrontString(originalString,laterSring: "重");
        
        // 获取汉字
        let chinese = xnStringHaveChinese(originalString);
 
        // 获取字符x 后面的字符串 (包含目标x)
        let newStirng = xnStringHaveTargetBackStirngNewMethod(originalString,targetSring: "LIFE重");
        
        
        print("原始字符串-->\(originalString)");
        print("从第7开始到第8个结束-->\(a)");
        print("从后面开始 截取6个字符-->\(b)");
        print("从前面开始 截取6个字符-->\(c)");
        print("获取字符E 后面的字符串-->\(d)");
        print("获取字符重 前面的字符串-->\(e)");
        print("获取汉字-->\(chinese)");
    }