This article is mainly to record some primary, but sometimes I have been easily ignored or forgotten, and only make a memorandum.
1), engagement /
/ In C , it can be used as a symbol (forgot the specification, is it called, sweating one ~), for example:
// this is Memo /
this is memo too
The above two lines are in C , the compiler will think it is a line.
However / usually only in the macro definition, because if it is a string, don't write the semicolil, such as: char * s = "how" "are" "" You? "; If it is a general statement, then directly change , Such as int sum = i j;
2)##
## is called an instruction paste, its English terminology called token-Pasting Operator, mainly in the macro definition. Use examples as follows:
#define paster (n) printf ("token" #n "=% d", token ## n)
INT token9 = 9;
Use the way as follows,
Paster (9); // Out: taken9 = 9
The above macro is equivalent to
Printf ("token" "9" "=% D", token9);
The result is:
Printf ("token9 =% D", token9);
3), division operator
/: Singhing, pay attention to the difference between the integer to remove the floating point number. If 3/2, the result = 1.3.0 / 2 is equal to 1.5.
%: Damo operator, 5% 3 = = 2
The first part is written first, and it will be sorted out in the future.
