比较 2 个单独列表中的 2 个属性

Question

我有2个单独的课程列表。1 列表是当前课程，另一个列表是过滤的课程。我想比较列表，如果课程存在或不存在，我想将过滤课程列表中的布尔值标记为真或假。下面是示例代码。

var currentCourses = new List<Course>

        {

            new Course{CourseNumber = "101", CourseSubject = "ART"},

            new Course{CourseNumber = "201", CourseSubject = "BIO"},

            new Course{CourseNumber = "301", CourseSubject = "CHEM"},

            new Course{CourseNumber = "401", CourseSubject = "CPSC"}

        };

        var filteredCourses = new List<Course>

        {

            new Course{CourseNumber = "101", CourseSubject = "ART"},

            new Course{CourseNumber = "401", CourseSubject = "CPSC"},

            new Course{CourseNumber = "501", CourseSubject = "DANC"},

            new Course{CourseNumber = "701", CourseSubject = "HIST"}

        };

我试过了：

foreach (var course in currentCourses)

        {

            foreach (var filteredCourse in filteredCourses)

            {

                if ((filteredCourse.CourseNumber === course.CourseNumber) && (filteredCourse.CourseSubject === course.CourseSubject))

                {

                    filteredCourse.AlreadyExists = true;

                }

                else

                {

                    filteredCourse.AlreadyExists = false;

                }

            }

        }

Answer 1

您应该在开始时将所有标志设置为 false，然后运行循环，并且仅在找到匹配项时才设置 true 标志。如果您运行当前代码，它将完成所有课程，如果匹配的课程不是最后一个，则标志将始终设置为 false，即使它已设置为 true。您还可以在找到匹配项时中断循环。所以像这样：foreach (var filteredCourse in filteredCourses)&nbsp; &nbsp; filteredCourse.AlreadyExists = false;foreach (var course in currentCourses){&nbsp; &nbsp; foreach (var filteredCourse in filteredCourses)&nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; if ((filteredCourse.CourseNumber == course.CourseNumber) && (filteredCourse.CourseSubject == course.CourseSubject))&nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; filteredCourse.AlreadyExists = true;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; break;&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; }}

Answer 2

您可以使用 LINQ：foreach (var f in filteredCourses){&nbsp; f.AlreadyExists = currentCourses.Any(c => (c.CourseNumber == f.CourseNumber&nbsp;&nbsp; &nbsp; && c.CourseSubject == f.CourseSubject));}