Problem: Write a Lex Program to check valid Mobile Number.
FLEX (Fast Lexical Analyzer Generator) is a tool/computer program for generating lexical analyzers (scanners or lexers) written by Vern Paxson in C around 1987. Lex reads an input stream specifying the lexical analyzer and outputs source code implementing the lexer in the C programming language. The function yylex() is the main flex function which runs the Rule Section.
Input: 7017175023 Output: Mobile Number Valid Input: 0001112223 Output: Mobile Number Invalid
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