简单的lex编程，详细见英文描述

Running the Lex program



1. Write the Lex specifications as described above in a file, say, prog1.l

2. On moon.cse.yzu.edu.tw, do the following:

flex prog1.l (Produces lex.yy.c as the output)

gcc lex.yy.c -lfl (Compile the C file and link with Lex library)

a.out (Run the executable, and type the input, followed by )

or, if the input is in a file, say, hw1.in, then do the following:

a.out < hw1.in-Write the LEX program as per the specifications below.

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Recognize　Action　

Arithmetic (+,-,*, /)　Print the operator along with the line number　

Relational (<, <=, >, >=, !=, ==)　Print the operator along with the line number　

Assignment (=)　Print the operator along with the line number　

Parenthesis (left and right ones)　No action for now　

Some set of Reserved Words (for, if, while, int, ...)　Print the Reserved word along with the line number　

Identifiers　Insert into a table and keep track of the line number　

Numbers　Print the number (should handle integer and floating point) along with the line number　



Keep explicit track of the current line number by recognizing "\n" as a separate token. Do not use the LEX line number variable.

At the end, print the number of distinct identifiers and the line numbers on which they occur.



Sample Input:



　int i, n, sum

　i =