## Find index of element in vector c++

Find an Element and Its Position in a Vector : find « STL Algorithms Non modifying sequence operations « C++ Tutorial. C++ Tutorial; STL Algorithms Non modifying sequence operations The code you quote in the comment: [code]vector::iterator indx=lower_bound(v.begin(),v.end(), num); int pos=indx-v.begin(); if(indx == v.end() || *indx!=num Returns a reference to the element at position n in the vector. The function automatically checks whether n is within the bounds of valid elements in the vector, throwing an out_of_range exception if it is not (i.e., if n is greater than, or equal to, its size).This is in contrast with member operator[], that does not check against bounds. Parameters n

In this post, we will see how to find index of the first occurrence of a given element in vector in C++. 1. std::find + std::distance. The simplest solution is to use the std::find algorithm defined in the header. The idea is to get the index using std::distance on the iterator returned by std::find which points to the found value. It returns the reference of element at index n in vector. If index n is out of range i.e. greater then size of vector then it will throw out_of_range exception. Let’s access element at index 3 using at() i.e. I need to find an element position in an std::vector to use it for referencing an element in another vector: however vector::size() returns size_t which corresponds to an unsigned integral type that can't directly store -1. Now I want to get the position of old_name in the Names vector, to use it in accessing certain element in Numbers vector. So that I can say: Numbers[position] = 3 ; // or whatever value assigned here. I tried using: vector :: const_iterator pos; pos = (find(Names.begin(), Names.end(), old_name_)) Numbers[pos] = 3; Thanks! just out of my curiosity what if my vector contains 1000 elements and using find will it be faster or I need to use some sort of pointer to array? – user2754070 Oct 18 '13 at 5:05 @user2754070 you would have to measure it, but I doubt you'll be faster than find in an optimized build. – juanchopanza Oct 18 '13 at 5:09 Finds the element in the given range of numbers. Returns an iterator to the first element in the range [first,last) that compares equal to val. If no such element is found, the function returns last. Function Template : InputIterator find (InputIterator first, InputIterator last, const T& val)

## k = find (X) returns a vector containing the linear indices of each nonzero element in array X. If X is a vector, then find returns a vector with the same orientation as X. If X is a multidimensional array, then find returns a column vector of the linear indices of the result. If X contains no nonzero elements or is empty, then find returns an

The function uses operator== to compare the individual elements to val . else std::cout << "Element not found in myints\n" ; // using std::find with vector and  std::find. #include. int main (). {. std::vector< int > vec { 10, 20, 30, 40 };. // Iterator used to store the position. // of searched element. std::vector< int >   Returns a reference to the element at position n in the vector. The function are the reference types to the elements of the container (see vector member types). Returns a reference to the element at position n in the vector container. are the reference types to the elements of the container (see vector member types). 26 Oct 2018 Nevertheless for an std::vector , it's not such a good deal because the How can we use a modern for loop and get access to the index of the  Return v.end() for empty vectors. std::vector v = {5, 2, 8, 10, 9}; int maxElementIndex  theory and abstract algebra, see Einstein notation and abstract index notation. In mathematics and computer programming, index notation is used to specify the elements of can also be written in terms of the elements of the vector (aka components), that is. a i + b i = c i {\displaystyle a_{i}+b_{i}=c_{i}} a_i + b_i = c_i.

### I am trying to get the index of an element in a vector of strings , to use it as an index in another vector of int type, is this possible ? Example: vector

Returns a reference to the element at position n in the vector. The function are the reference types to the elements of the container (see vector member types). Returns a reference to the element at position n in the vector container. are the reference types to the elements of the container (see vector member types). 26 Oct 2018 Nevertheless for an std::vector , it's not such a good deal because the How can we use a modern for loop and get access to the index of the  Return v.end() for empty vectors. std::vector v = {5, 2, 8, 10, 9}; int maxElementIndex  theory and abstract algebra, see Einstein notation and abstract index notation. In mathematics and computer programming, index notation is used to specify the elements of can also be written in terms of the elements of the vector (aka components), that is. a i + b i = c i {\displaystyle a_{i}+b_{i}=c_{i}} a_i + b_i = c_i.

### Find Maximum and Minimum element in a Set in C++ STL; How to find the minimum and maximum element of an Array using STL in C++? How to find the maximum element of an Array using STL in C++? Last element of vector in C++ (Accessing and updating) How to find the sum of elements of a Vector using STL in C++? How to find common elements between two

26 Oct 2018 Nevertheless for an std::vector , it's not such a good deal because the How can we use a modern for loop and get access to the index of the  Return v.end() for empty vectors. std::vector v = {5, 2, 8, 10, 9}; int maxElementIndex  theory and abstract algebra, see Einstein notation and abstract index notation. In mathematics and computer programming, index notation is used to specify the elements of can also be written in terms of the elements of the vector (aka components), that is. a i + b i = c i {\displaystyle a_{i}+b_{i}=c_{i}} a_i + b_i = c_i. initial size. For example, the following code constructs a QVector with 200 elements: QVector uses 0-based indexes, just like C++ arrays. If you want to find all occurrences of a particular value in a vector, use indexOf() or lastIndexOf() . 21.1.3 Finding values. match(v, table). Returns an integer vector containing the R style numerical index (starting from 1) of the element of vector table that match

## Example. To find the largest or smallest element stored in a vector, you can use the methods std::max_element and std::min_element, respectively.These methods are defined in header. If several elements are equivalent to the greatest (smallest) element, the methods return the iterator to the first such element.

I am trying to get the index of an element in a vector of strings , to use it as an index in another vector of int type, is this possible ? Example: vector  The function uses operator== to compare the individual elements to val . else std::cout << "Element not found in myints\n" ; // using std::find with vector and  std::find. #include. int main (). {. std::vector< int > vec { 10, 20, 30, 40 };. // Iterator used to store the position. // of searched element. std::vector< int >   Returns a reference to the element at position n in the vector. The function are the reference types to the elements of the container (see vector member types). Returns a reference to the element at position n in the vector container. are the reference types to the elements of the container (see vector member types). 26 Oct 2018 Nevertheless for an std::vector , it's not such a good deal because the How can we use a modern for loop and get access to the index of the

It returns the reference of element at index n in vector. If index n is out of range i.e. greater then size of vector then it will throw out_of_range exception. Let’s access element at index 3 using at() i.e. I need to find an element position in an std::vector to use it for referencing an element in another vector: however vector::size() returns size_t which corresponds to an unsigned integral type that can't directly store -1. Now I want to get the position of old_name in the Names vector, to use it in accessing certain element in Numbers vector. So that I can say: Numbers[position] = 3 ; // or whatever value assigned here. I tried using: vector :: const_iterator pos; pos = (find(Names.begin(), Names.end(), old_name_)) Numbers[pos] = 3;