quicksort [] = []
quicksort (x:xs) = quicksort [y | y <- xs, y < x] ++ [x] ++ quicksort [y | y <- xs, y >= x]
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#include <stdio.h>
int main(void) {
char *ptr = "ABC";
int i;
for(i=0; ptr[i-1]; i++)
putchar(ptr[i]);
putchar('\n');
printf("%s", ptr);
return (0);
}