如何在C ++中将#define是否像python一样

Question

I know that I can define something like

#define LESS(x, y) if(x < y)

so I wonder can I define if in c++ to be python-like template or not? such as

if x < y: do something instead of if(x < y) do something

Answer 1

To put it shortly - no .

from cplusplus.com :

When the preprocessor encounters this directive, it replaces any occurrence of identifier in the rest of the code by replacement. This replacement can be an expression, a statement, a block or simply anything. The preprocessor does not understand C++, it simply replaces any occurrence of identifier by replacement.

What you want is something like this

#define if(x):(y) if(x){##y##};

Nevertheless, colon is a keyword and can't be used for identifier, so it breaks your macro definition. There's no way to escape it.