The equal function in C++ Algorithm compares the elements in two containers and returns true if all elements in both containers match. The first range is denoted by [first1, last1) and the second range starts from first2.
Syntax
template<class InputIterator1, class InputIterator2> bool equal(InputIterator1 first1, InputIterator1 last1,InputIterator2 first2);
template<class InputIterator1, class InputIterator2, class BinaryPredicate> bool equal(InputIterator1 first1, InputIterator1 last1, InputIterator2 first1, BinaryPredicate pred);
Parameter
It serves as an input iterator pointing to the initial element within the range [first1, last1).
It serves as an input iterator pointing to the final element within the range [first1, last1).
It serves as an input iterator pointing to the initial element within the [first2, last2) range.
"pred : It is a binary function that takes two elements as parameters and executes the specified operation."
Return value
The function will output true if all elements in both containers are identical, otherwise it will return false.
Example 1
#include<iostream>
#include<algorithm>
#include<vector>
using namespace std;
bool newpredicate(int m, int n)
{
return(m==n);
}
int main()
{
int newints[]={20,40,60,80,100};
std::vector<int> newvector(newints, newints+5);
if(std::equal(newvector.begin(),newvector.end(),newints))
std::cout<<"Both the containers have matching elements.\n";
else
std::cout<<"Both the containers have difference elements.\n";
newvector[3]=81;
if(std::equal(newvector.begin(),newvector.end(),newints,newpredicate))
std::cout<<"Both the containers have equal containers.\n";
else
std::cout<<"Both the containers do not have equal elements. \n";
return 0;
}
Output:
Both the containers have matching elements.
Both the containers do not have equal elements.
Example 2
#include<bits/stdc++.h>
using namespace std;
int main()
{
int u1[]={10,20,30,40,50};
std::vector<int> vec_1(u1,u1+sizeof(u1)/sizeof(int));
std::cout<<"The vector consists of:";
for(unsigned int k=0; k<vec_1.size(); k++)
std::cout<<" "<<vec_1[k];
std::cout<<"\n";
if(std::equal(vec_1.begin(),vec_1.end(),u1))
std::cout<<"Both the containers have equal elements.\n";
else
cout<<"Both containers have different elements.";
}
Output:
The vector consists of: 10, 20,30,40,50
Both the containers have equal elements.
Complexity
The function exhibits linear time complexity from the initial element to the final element.
Data races
Objects in both ranges are accessed.
Exceptions
The function will raise an exception if any of its arguments also raises one.
