Anyone know why cant erase that vector???

if(v[x]==vecfileword[y])
vecfileword.erase(y);

How to compare two vector and if the same vector then erase it..How??
my vector is string

//compareIndex();
for(int x=0,y=0;0<v.size(x);x++)
{
while(0<vecfileword.size(y))
{
if(v[x]==vecfileword[y])
vecfileword.erase(y);


y++;
}
}

Correct??? But still got error

Can You show me how to use pop_back as well in this code?