C++

In code, every { must have a corresponding }

Similarly, every [ must have a corresponding ] and every ( must have a corresponding )

Furthermore, the symbols must be appropriately closed in the sense that they are closed in the reverse of the order that they are opened.

For example:

{[]} is a legal sequence

{[}] is NOT a legal sequence because the } was closed when the [ was the last character that was opened

[[]] is a legal sequence

[{}{}] is a legal sequence

{{{{{{{{{{{{{{{{}}}}}}}}}}}}}}}} is a legal sequence

{ is NOT a legal sequence because the { is never closed

Going further:

for(int i = 0; i < 10; i++){ cout << i; } is a legal sequence

And so on.

How do I write a program that reads in a .cpp file and determines if the {},[],() are legally sequenced WITHOUT using the standard library stack class and while using the += and -= operators overloads?