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authorbk2dcradle <ankitsultana@gmail.com>2016-01-05 13:25:56 +0530
committerbk2dcradle <ankitsultana@gmail.com>2016-01-05 13:25:56 +0530
commita5730e4ab931b8355704d35ee08acef75435bd83 (patch)
tree53a32cf6d903a79f4e4bf7e6a2a21252ca787faa
parent54c67dfb38d1bb2a9dc004b3244d2ae3102107f3 (diff)
Update
-rw-r--r--c++.html.markdown48
1 files changed, 7 insertions, 41 deletions
diff --git a/c++.html.markdown b/c++.html.markdown
index 6033ca06..c1bacf6a 100644
--- a/c++.html.markdown
+++ b/c++.html.markdown
@@ -809,7 +809,7 @@ void doSomethingWithAFile(const std::string& filename)
// object right at the location where it is invoked or passed as
// an argument to a function.
-// Example consider sorting a vector of pairs using the second
+// For example, consider sorting a vector of pairs using the second
// value of the pair
vector<pair<int, int> > tester;
@@ -820,7 +820,7 @@ tester.push_back(make_pair(5, 0));
// Pass a lambda expression as third argument to the sort function
// sort is from the <algorithm> header
-sort(tester.begin(), tester.end(), [](const pair<int, int> &lhs, const pair<int, int> &rhs) {
+sort(tester.begin(), tester.end(), [](const pair<int, int>& lhs, const pair<int, int>& rhs) {
return lhs.second < rhs.second;
});
@@ -834,48 +834,22 @@ for(int i = 0; i < 3; i++){
dog_ids.push_back(i);
}
-int weight[3];
-weight[0] = 30, weight[1] = 50, weight[2] = 10;
+int weight[3] = {30, 50, 10};
// Say you want to sort dog_ids according to the dogs' weights
// So dog_ids should in the end become: [2, 0, 1]
// Here's where lambda expressions come in handy
-sort(dog_ids.begin(), dog_ids.end(), [weight](const int &lhs, const int &rhs) {
+sort(dog_ids.begin(), dog_ids.end(), [&weight](const int &lhs, const int &rhs) {
return weight[lhs] < weight[rhs];
});
-// Note we captured "weight" in the above example.
+// Note we captured "weight" by reference in the above example.
// lambda are really useful for the case of structs
// You can use lambda expressions instead of overloading
// the "<" operator
-struct dog{
- int weight, age;
-}dogs[3];
-
-dogs[0].weight = 30, dogs[0].age = 4;
-dogs[1].weight = 40, dogs[1].age = 10;
-dogs[2].weight = 20, dogs[2].age = 9;
-
-// Say I want to sort the dogs array by the dogs' weights
-
-sort(dogs, dogs+3, [](const dog &lhs, const dog &rhs) {
- return lhs.weight < rhs.weight;
- });
-// dogs is now sorted according to their weight
-
-// Do something with the dogs
-
-// Now I want to sort the dogs by in descending order of their age
-
-sort(dogs, dogs+3, [](const dog &lhs, const dog &rhs) {
- return lhs.age > rhs.age;
- });
-// dogs is now sorted in descending order of their age
-
-
///////////////////////////////
// Range For (C++11 and above)
///////////////////////////////
@@ -884,24 +858,16 @@ sort(dogs, dogs+3, [](const dog &lhs, const dog &rhs) {
int arr[] = {1, 10, 3};
for(int elem: arr){
- cout<<elem<<'\n';
+ cout << elem << endl;
}
// You can use "auto" and not worry about the type of the elements of the container
-// Caveat: Don't assign inside the range for loop
// For example:
for(auto elem: arr) {
- elem = -1;
+ // Do something with each element of arr
}
-// "arr" remains unchanged
-
-// Why doesn't it change?
-// What actually is happening is that the value of "arr[i]" is stored in
-// the variable "elem" in every iteration. So assigning "elem" doesn't assign "arr[i]".
-// For more, checkout: http://en.cppreference.com/w/cpp/language/range-for
-
/////////////////////
// Fun stuff
/////////////////////