Answer:
Braces {}.
Explanation:
In C++ the boundary of a block are defined by the {} braces.
() parentheses are used to pass arguments to the functions.
[] brackets are used to mention the size of the array.
' ' quotes are used for characters.
for ex:-
int main()
{ //line 1
for(int i=0;i<10;i++)
{ //line 2
cout<<i<<" ";
} //line 3
cout<<endl;
return 0;
} //line 4
The boundary of for loop is from line 2 to line 3 and the boundary of main function is line 1 to line 4.
