Sum()方法计算集合中数字项的总和。
下面的示例演示原始集合上的Sum()方法。
IList<int> intList = new List<int>() { 10, 21, 30, 45, 50, 87 };
var total = intList.Sum();
Console.WriteLine("总计: {0}", total);
var sumOfEvenElements = intList.Sum(i => {
if(i%2 == 0)
return i;
return 0;
});
Console.WriteLine("偶数元素的总计: {0}", sumOfEvenElements );总计：243 偶数元素的总计：90
下面的示例计算学生集合中所有学生的年龄总和，以及成年学生的人数。
IList<Student> studentList = new List<Student>>() {
new Student() { StudentID = 1, StudentName = "John", Age = 13} ,
new Student() { StudentID = 2, StudentName = "Moin", Age = 21 } ,
new Student() { StudentID = 3, StudentName = "Bill", Age = 18 } ,
new Student() { StudentID = 4, StudentName = "Ram" , Age = 20} ,
new Student() { StudentID = 5, StudentName = "Ron" , Age = 15 }
};
var sumOfAge = studentList.Sum(s => s.Age);
Console.WriteLine("学生年龄总和: {0}", sumOfAge);
var numOfAdults = studentList.Sum(s => {
if(s.Age >= 18)
return 1;
else
return 0;
});
Console.WriteLine("成年学生人数: {0}", numOfAdults);// 学生集合
Dim studentList = New List(Of Student) From {
New Student() With {.StudentID = 1, .StudentName = "John", .Age = 13},
New Student() With {.StudentID = 2, .StudentName = "Moin", .Age = 21},
New Student() With {.StudentID = 3, .StudentName = "Bill", .Age = 18},
New Student() With {.StudentID = 4, .StudentName = "Ram", .Age = 20},
New Student() With {.StudentID = 5, .StudentName = "Ron", .Age = 15}
}
Dim sumOfAge = studentList.Sum(Function(s) s.Age)
Console.WriteLine("学生年龄总和: {0}", sumOfAge)
Dim numOfAdults = studentList.Sum(Function(s)
if(s.Age >= 18)
return 1
else
return 0
end if
end function)
Console.WriteLine("成年学生人数: {0}", numOfAdults)学生年龄总和：87 成年学生人数：3
C# 查询语法中不支持Sum运算符。
// 学生集合
Dim studentList = New List(Of Student) From {
New Student() With {.StudentID = 1, .StudentName = "John", .Age = 13},
New Student() With {.StudentID = 2, .StudentName = "Moin", .Age = 21},
New Student() With {.StudentID = 3, .StudentName = "Bill", .Age = 18},
New Student() With {.StudentID = 4, .StudentName = "Ram", .Age = 20},
New Student() With {.StudentID = 5, .StudentName = "Ron", .Age = 15}
}
Dim totalAge = Aggregate st In studentList Into Sum(st.Age)
Console.WriteLine("所有年龄段的总和: {0}", totalAge);所有年龄段的总和：87