Lex program to check whether the input is digit or not
Lex is a computer program that generates lexical analyzers. Lex reads an input stream specifying the lexical analyzer and outputs source code implementing the lexer in the C programming language.
Prerequisite: Flex (Fast lexical Analyzer Generator).
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Given an input, the task is to check if the input is digit or not.
Examples:
Input: 28 Output: digit Input: a Output: not a digit. Input: 21ab Output: not a digit.
Below is the implementation:
/* Lex program to check whether input is digit or not. */%{#include<stdio.h>#include<stdlib.h>%}/* Rule Section */%%^[0-9]* printf("digit");^[^0-9]|[0-9]*[a-zA-Z] printf("not a digit");. ;%%int main(){ // The function that starts the analysis yylex(); return 0;} |
Output:
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