Plz explain me.... int d = s2.compare(s2.size() -1,1,s3,s3.size() -1,1);

Question

#include <iostream>
#include <string>
using namespace std;

int main()
{
string s1("Road");
string s2("Read");
string s3("Red");

int a = s1.compare(0,2,s2,0,2);
int b = s2.compare(0,2,s1,0,2);
int c = s2.compare(0,2,s3,0,2);
int d = s2.compare(s2.size() -1,1,s3,s3.size() -1,1);

cout<< "a ="<<a ;
cout<<"\n"<<"b ="<<b<<"\n";
cout<<"c ="<<c<<"\n";
cout<<"d ="<<d;
return 0;
}

Answer 1

I would look up the compare function. quickly though.

line int a: s1 compared to s2 both starting at 0 for a length of 2

Answer 2

size of s2 - 1. which equals 3.
do the math and those become the inserted values like above. (3,1,s3,2,1)

Answer 3

they are equal as they are both "d"

do you understand now?

If the "letters" compared are the same return 0
if there is a difference it will return either 1 or -1 depending on the difference
a to b = 1
b to a = -1

Answer 4

can you explain me this line ?
int d=s2.compare(s2.size()-1,1,s3,s3.size()-1,1);

Answer 5

when we run this code, value of d is 0...how its possible?