You forgot the brackets:
void output
{
float amount;
amount=qty*price;
cout<<"\n total amount="<<amount;
};
Should be:
void output()
{
float amount;
amount=qty*price;
cout<<"\n total amount="<<amount;
};
If you double click the error in VS, it will take you straight to the line it found a problem with. For command line compilers, they will list the filename, line and column numbers with the error message, and CTRL+G will take you to a specific line number in most text editors.
But ... do yourself a favour and sort out your indentation - it makes you code a lot easier to read.