In <stdlib.h>

#define repeat(INT) for(int i{ 0 }; i < INT; ++i)

#define rep() while(true)

#define until(BOOL) while(!(BOOL))

#define rep_until(BOOL, todo) \
{ \
    ##todo \
                                                             \
    while (BOOL) { \
       ##todo \
    } \
};