Lex program to check whether given string is Palindrome or Not
Last Updated :
01 May, 2019
Problem: Write a Lex program to check whether given string is Palindrome or Not.
Explanation:
Lex is a computer program that generates lexical analyzers and was written by Mike Lesk and Eric Schmidt. Lex reads an input stream specifying the lexical analyzer and outputs source code implementing the lexer in the C programming language.
Description: A string is said to be palindrome if reverse of the string is same as string. For example, “abba” is palindrome, but “abbc” is not palindrome.
Examples:
Input: Enter a string : naman
Output: Given string is Palindrome
Input: Enter a string : geeksforgeeks
Output: Given string is not Palindrome
Implementation:
%
{
int i, j, flag;
%
}
% %
[a - z A - z 0 - 9]*
{
for (i = 0, j = yyleng - 1; i <= j; i++, j--) {
if (yytext[i] == yytext[j]) {
flag = 1;
}
else {
flag = 0;
break ;
}
}
if (flag == 1)
printf ( "Given string is Palindrome" );
else
printf ( "Given string is not Palindrome" );
}
% %
int main()
{
printf ( "Enter a string :" );
yylex();
return 0;
}
int yywrap()
{
return 1;
}
|
Output:
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