C++中Lambda表达式的语法与实例

[捕获列表] (参数) mutable 或 exception 声明 -> 返回值类型 {函数体}

//计算两个值的和
auto func = [](int a, int b) -> int{return a+b;};
//当返回值的类型是确定时，可以忽略返回值
auto func = [](int a, int b){return a + b;};
//调用
int sum = func(1, 3);

class Labmda
{
public:
    const int test;
    Labmda(int value):test(value)
    {
    }
public:
    int run(int a, int b)
    {
        return a + b + test;
    }
}

int main()
{
    int test = 10;
    auto func = Labmda(test);
    int sum = func.run(1, 3);
}

//使用Lambda 表达式的写法
int main()
{
    int test = 10;
    auto func = [test](int a, int b){return a + b + test;};
    int sum = func(1, 3);
}

int test = 10;
//编译报错，test成员不能修改
auto func = [test](int a, int b){test = 8; return a + b + test;}; 
//编译正常
auto func = [test](int a, int b)mutable {test = 8; return a + b + test;}; 

int test = 10;
auto func = [=](int a, int b){return a + b + test;};
auto func2 = [test](int a, int b){return a + b + test;};
int sum = func(1, 3); //sum等于14

int test = 10;
auto func = [=](int a, int b){return a + b + test;};
test = 5;
int sum = func(1, 3); //sum还是等于14

int test = 10;
auto func = [&](int a, int b){test = 5; return a + b + test;};
auto func2 = [&test](int a, int b){test = 5; return a + b + test;};
int sum = func(1, 3); //sum等于9，test等于5

int test = 10;
auto func = [=](int a, int b){return a + b + test;};
test = 5;
int sum = func(1, 3); //sum等于9，test等于5