When I was studying, I suddenly saw the usage of two lambda expressions in the example. [](){}I []{}()suddenly felt confused
about this usage . After checking, the former is a standard lambda expression usage , while the latter is a shorthand version of lambda + call, that is, omitted () used for parameter passing, and calls itself directly after constructing the anonymous function . For example:[]{}()[](){}[]{}()
int c = [](int n){
return [n](int x){
return n + x;
}(1);
};
a = c(2);
int c = [](int n){
return [n]{
return 1;
}();
}(2);