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| /** Convert Roman numerals given on the command line to decimals. | |
| $ ragel -F0 -p -o roman_numerals.c roman_numerals.rl | |
| $ cc -o roman_numerals roman_numerals.c | |
| $ ./roman_numerals IX XII | |
| 9 | |
| 12 | |
| $ ./roman_numerals IIX && exit 1 || echo invalid | |
| invalid | |
| */ | |
| #include <string.h> | |
| #include <stdio.h> | |
| #include <stdlib.h> | |
| %%{ | |
| machine roman_numerals; | |
| write data; | |
| }%% | |
| int main(int argc, char* argv[]) { | |
| if (argc < 2) { | |
| fputs("Usage: roman_numerals <text>...\n", stderr); | |
| exit(EXIT_FAILURE); | |
| } | |
| for (int i = 1; i < argc; ++i) { | |
| int n, cs; | |
| char *p = argv[i], *pe = p + strlen(p), *eof = pe; | |
| %%{ | |
| thousands = ('M' %{ n += 1000; }){,3}; | |
| hundreds = "CM" %{ n += 900; } | |
| | "CD" %{ n += 400; } | |
| | ('D' %{ n += 500; } )? ('C' %{ n += 100; }){,3}; | |
| tens = "XC" %{ n += 90; } | |
| | "XL" %{ n += 40; } | |
| | ('L' %{ n += 50; } )? ('X' %{ n += 10; }){,3}; | |
| units = "IX" %{ n += 9; } | |
| | "IV" %{ n += 4; } | |
| | ('V' %{ n += 5; } )? ('I' %{ n += 1; }){,3}; | |
| numeral = thousands hundreds tens units; | |
| main := numeral > { n = 0; } ; | |
| write init; | |
| write exec; | |
| }%% | |
| if (!n || cs == roman_numerals_error) | |
| exit(EXIT_FAILURE); | |
| printf("%d\n", n); /* print result */ | |
| } | |
| return 0; | |
| } |
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