Can two different variables in the same program may have the same name?

Answer 1

Yes, so long as they are declared in separate scopes. But just because it CAN be done, it doesn't mean it SHOULD be done. When you need to access both variables within the same scope, you need to have some way of differentiating them. You could use namespaces to explicitly declare their scope, but your code will be that much easier to read if you simply give each variable an unique name to begin with. This could be as simple as prefixing variables with "g_" for global scope, "f_" for file scope and "m_" for class scope. That way, local function variables don't require prefixes.

The following example demonstrates redeclaration of variables x and y within the same function (within nested scopes), thus making it impossible to access the previous declarations until the new declarations fall from scope. While this can be useful to protect the original variables, there are far better, less ambiguous ways of achieving this: consistent use of the const keyword along with unique identifiers; or simply passing the values (by value) to another function altogether. Ultimately, the fewer ambiguities in your code the easier it will be to read and maintain.

void foo( int x )

{

printf( "x (function level) = %d\r\n", x );

int y = x;

printf( "y (function level) = %d\r\n", y );

if( y )

{

int x=y; // new declaration -- protects previous declaration.

++x;

printf( "x (code block 1) = %d\r\n", x );

int y=x; // new declaration -- protects previous declaration.

printf( "y (code block 1) = %d\r\n", y );

if( y )

{

int x=y; // new declaration -- protects previous declaration.

++x;

printf( "x (code block 2) = %d\r\n", x );

}

printf( "x (code block 1) = %d\r\n", x );

}

printf( "x (function level) = %d\r\n", x );

printf( "y (function level) = %d\r\n", y );

}

int main()

{

foo( 1 );

return( 0 );

}

Answer 2

Of course