c / intermediate
Snippet
Stringification and Concatenation in Macros
The '#' operator converts a macro argument into a string literal (stringification). The '##' operator joins two tokens together during preprocessing (concatenation), allowing for dynamic generation of variable names or code blocks.
snippet.c
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#include <stdio.h>#define DEBUG_PRINT(var) printf(#var " = %d\n", var)#define MAKE_NAME(prefix, suffix) prefix ## _ ## suffixint main() {int my_val = 42;DEBUG_PRINT(my_val);int MAKE_NAME(user, id) = 101;printf("user_id = %d\n", user_id);return 0;}
Breakdown
1
#var
Converts the name of the variable passed to the macro into a string literal.
2
prefix ## _ ## suffix
Glues tokens together; for example, 'user' and 'id' become the single identifier 'user_id'.