Why doesn’t std::vector or other containers have length as a member variable, instead of a function? Because it would be writable if it was a public member variable. Since it makes no sense to write to the size member of a vector, the designers made the size member private and provided a size() method to … Read more
Q1: How to check if a value exists in hashmap? You need to iterate through and check if such item exists. You can use `std::find_if() with a lambda or do that through a loop. If you do that quite often you may want to index values as well (see below) Q2: How to iterate through … Read more
See the reference: template< class Key, class T, class Compare = std::less<Key>, class Allocator = std::allocator<std::pair<const Key, T> > > class map; http://en.cppreference.com/w/cpp/container/map An std::map takes a comparator that tells if the first argument is less than the second. Not if they are equal. Otherwise it could not build a binary tree. You don’t need … Read more
C++ How to distinguish Multimap with duplicate keys with value and and Unique keys with values in different map containers with O(n) traversal solved C++ How to distinguish Multimap with duplicate keys with value and and Unique keys with values in different map containers with O(n) traversal
Not the most elegant solution but this should work #include <iostream> #include <vector> #include <string> #include <sstream> using namespace std; vector<string> split(string str, char delimiter) { vector<string> internal; stringstream ss(str); string tok; while(getline(ss, tok, delimiter)) { internal.push_back(tok); } return internal; } int main(int argc, char **argv) { string str = “My name is bob.I am … Read more
Your fill function takes the parameter a by value, which means a copy is made. No changes to a inside the function will affect the variable you passed to the function. I suggest you make the function pass the object by reference: void fill(stack<int>& a, int cap) Now changes to a will update the object … Read more
The error is on this line: key[j]=words[index]; key is a std::string key; Therefore, key[j] is a char. words is a std::vector<std::string> words; Therefore, words[index] is a std::string. You cannot assign a std::string to a char. C++ doesn’t work this way. Your code is equivalent to the following: char a; std::string b; a=b; It is not … Read more
You dont need to worry about memory leaks, in your case you use std::vector which uses RAII to make sure no memory is leaked. With STL containers you can “leak” in such case on;y if you do not shrink your vector after using remove algorithm. Below is fix to your code, and not entire rewrite. … Read more
std::vector<student_t> st; for(unsigned i = 0; i < 10; ++i) st.push_back(student_t()); std::sort(st.begin(), st.end(), &compare); You could also use this vector constructor instead of lines 1-2: std::vector<student_t> st (10 /*, student_t() */); Edit: If you want to enter 10 students with the keyboard you can write a function that constructs a student: struct student_t &enter_student() { … Read more
Two problems. First, you cannot reorder the elements of a set. Their ordering criteria is determined upon construction, it is a fundamental part of the object. This is necessary in order for it to achieve O(log n) lookups, insertions, and deletions, which is part of the promises of std::set. By default, it will use std::less<Edge>, … Read more
In this declaration: vector<int>::iterator rit_i,rit_j,initial = vec.end(); only initial is initialized with vec.end(). To make it do what I think you expect, you have to write vector<int>::iterator rit_i = vec.end(), rit_j = vec.end(), initial = vec.end(); or vector<int>::iterator rit_i,rit_j,initial; rit_i = rit_j = initial = vec.end(); or something to that effect. solved segmentation fault for … Read more
When run, x contains in order: 2 4 7 11 12 14 17 y contains in order: 11 2 4 7 My hunch is that the set reverses the operator to check for equality (since a set only contains unique values). Thus only unique values of a%10 exist. 3 solved What values are inserted in … Read more
In C++, the begin() member function returns a pointer (or iterator) to the front (a lot of the time, anyways). You can access the first element with begin(), but you have to dereference it (like a pointer) first: cout << *s.begin(); // 5 Here is a demo: https://repl.it/JQiU/0 solved Is the code valid. If i … Read more
Solution simple as always: void RemoveDuplicates (std::string& input) { std::string::iterator it = std::unique(input.begin(), input.end()); input.erase(it, input.end()); std::cout << “New input = “<< input << std::endl; } Another solution to return a new string: std::string RemoveDuplicates (const std::string& input) { std::string newT(input); std::string::iterator it = std::unique(newT.begin(), newT.end()); newT.erase(it, newT.end()); return newT; } If desired result is … Read more
std::find and other similar functions return the Iterator to the found element. If the element is not found in the container, the returned Iterator points to the end of the specified range (which in your case is std::end). So, find(a.begin(), a.end(), s-i) == a.end() means that element s-i is not in the container a. cpp … Read more