Thread: wts diff b/w int i=100 , i=100 in constructor?

While executing below programs i getting different results

Code:

#include<iostream>
using namespace std;
class c
{
public :
int i;
c();
};

c::c()
{
int i=20;
}
int main()
{
c c1;
cout<<c1.i<<"\n";
return 0;
}

putput:1200034523

Code:

#include<iostream>
using namespace std;
class c
{
public :
int i;
c();
};

c::c()
{
i=20;
}
int main()
{
c c1;
cout<<c1.i<<"\n";
return 0;
}

output : 20



anybody let me know the why if i place int in constructor it reflecting on result?


i look for your further replys

Code:

c::c()
{
int i=20;
}

declares a local variable named i that only exists within the c() function. When c() ends, that i that you declared goes away. This means the class version of i is never touched, so it contains whatever garbage value that memory location had.

Your second version without the int keyword in the constructor specifically sets the class version of i to 20.