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Diffstat (limited to 'md/writeup/c_macro_tricks.md')
| -rw-r--r-- | md/writeup/c_macro_tricks.md | 37 |
1 files changed, 18 insertions, 19 deletions
diff --git a/md/writeup/c_macro_tricks.md b/md/writeup/c_macro_tricks.md index 4068272..e9f9d0f 100644 --- a/md/writeup/c_macro_tricks.md +++ b/md/writeup/c_macro_tricks.md @@ -15,10 +15,10 @@ this allows to see resulting source that going to be compiled, macro errors could be hard to debug, but this is first thing, test them before and then be sure that everything works. Lets continue with some more deep stuff. -<!-- ####################################################################### --> + ## __VA_ARGS__ keyword -<!-- ####################################################################### --> + ### Single argument macros Writting macros with single argument @@ -42,14 +42,14 @@ F(}) any kind of argument can be passed to macro, and that allows to make some tricks #### Result -``` +```c int main (){ printf("hello world\n"); } ``` -<!-- ####################################################################### --> + ### Multi argument macro writting macro with multiple unamed arguments @@ -74,7 +74,7 @@ Previouse example works just fine, but if add multiple arguments the __VA_ARGS__ just prints them as a whole string #### Result -``` +```c int main (){ printf("hello world\n"); @@ -84,7 +84,7 @@ printf("hello world\n"); ``` -<!-- ####################################################################### --> + ### Mixing named arguments and unamed arguments Mixing together named and unnamed arguments @@ -108,7 +108,7 @@ F2(int main,{my code},{more code}) #### Result -``` +```c 2,3,4,5 1 @@ -116,7 +116,7 @@ F2(int main,{my code},{more code}) int main ``` -<!-- ####################################################################### --> + ## Define struct with macros Lets move to some more practical example lets just define macro that going to @@ -172,7 +172,6 @@ struct add {int a; int b;};; struct dirst {int c; ;};; ``` -<!-- ####################################################################### --> ## Detect number of arguments There is one trick that can be used to detect number of arguments passed to @@ -222,12 +221,12 @@ F(1,2,3,4,5) 5 ``` -<!-- ####################################################################### --> + ## Variable argument macro match macro according number of arguments Detect number of arguments and match macro according to number of arguments -``` +```c #define FUN3(X1,X2,X3,...) "there is 3" #define FUN2(X1,X2,...) "there is 2" #define FUN1(X1,...) "there is 1" @@ -237,14 +236,14 @@ Detect number of arguments and match macro according to number of arguments ``` #### Source -``` +```c FUN(add,int a,int b); FUN(mul,int a,int b,int c); FUN(div,int a); ``` #### Result -``` +```c void add ( "there is 2"); void mul ( "there is 3"); void div ( "there is 1"); @@ -257,7 +256,7 @@ void div ( "there is 1"); Best part of it that it can match also typdefed structures. So now macroses can contain typechecking -``` +```c #define type_str(T) _Generic( (T), int: "int",\ long: "long",\ A: "A",\ @@ -287,7 +286,7 @@ int main() #### Result -``` +```block long int A @@ -305,7 +304,7 @@ default: "UNK UNK" ) ``` #### Source -``` +```c typedef struct A { @@ -336,7 +335,7 @@ int int A A ``` ### Generic printf -``` +```c #define FF "%f " #define FS "%s " #define FD "%d " @@ -355,7 +354,7 @@ A A ``` #### Source -``` +```c int main() { A a; @@ -372,7 +371,7 @@ int main() #### Result -``` +```bash 1 2.000000 3 4 big float 0.010000 |