[c] matlex

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///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
1.Problem Statement : Lex programs to recognize Keywords.
Description : token can look like anything that is useful for processing an input text stream or
text file.
Source Code:
%{
#include<stdio.h>
%}
%%
int|float|char { printf(" data type: %s",yytext); }
%%
int main()
{
yylex();
return(0);
}
int yywrap()
{
}
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
2.Problem Statement : Lex programs to recognize String ending with 00.
Description : token can look like anything that is useful for processing an input text stream or
text file.
Source Code:
%{
#include<stdio.h>
%}
%%
[a-z A-Z 0-9]++00 { printf("string is acepted",yytext);}
.* { printf("not acepted",yytext);}
%%
int main()
{
yylex();
return(0);
}
int yywrap()
{
}
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
3.Problem Statement : Program to recognize the strings which are starting or ending with ‘k’.
Description : token can look like anything that is useful for processing an input text stream or
text file.
Source Code:
%{
#include<stdio.h>
%}
begin-with-k k.*
end-with-k .*k
%%
{begin-with-k} { printf(" %s is a word that begin with k",yytext);}
{end-with-k} { printf(" %s is a word that end with k",yytext);}
%%
int main()
{
yylex();
return(0);
}
int yywrap()
{
}
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
4.Problem Statement : program to assign line numbers for source code.
Description : token can look like anything that is useful for processing an input text stream or
text file.
Source Code:
%{
#include<stdio.h>
int lineno=0;
%}
line .*\n
%%
{line} { printf("%d .%s",lineno++,yytext); }
%%
int main(int argc,char **argv)
{
if(argc>1)
{
FILE *file;
file=fopen(argv[1],"r");
if(!file)
{
printf("could not open %s\n",argv[1]);
exit(0);
}
yyin=file;
}
yylex();
printf("\n\n");
return 0;
}
int yywrap()
{
return 0;
}
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
5.Problem Statement : Program to recognize the numbers which has 1 in its 5th position from
right.
Description : token can look like anything that is useful for processing an input text stream or
text file.
Source Code:
%{
#include<stdio.h>
%}
%%
[0-9]*1[0-9]{4} { printf("acepted:");}
[0-9]*1[0-9] { printf("NOT acepted:");}
%%
int main()
{
yylex();
return(0);
}
int yywrap()
{
}
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
6.Lex Specification to Replace Space with $
%{
#include <stdio.h>
%}
%%
[ ] { printf("$"); } // Replaces each space with a dollar sign
%%
int main()
{
yylex();
return 0;
}
int yywrap() {
return 1;
}
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
7.Lex Specification to Identify the Number Divisible by 9
%{
#include <stdio.h>
%}
%%
[0-9]+ { int num = atoi(yytext); if (num % 9 == 0) printf("%s is divisible by 9\n", yytext); }
%%
int main()
{
yylex();
return 0;
}
int yywrap() {
return 1;
}
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
8. Lex Specification to Identify Identifier and Functional Identifier
%{
#include <stdio.h>
%}
%%
[a-zA-Z_][a-zA-Z0-9_]* { printf("Identifier: %s\n", yytext); }
[a-zA-Z_][a-zA-Z0-9_]*\( { printf("Functional Identifier: %s\n", yytext); }
%%
int main()
{
yylex();
return 0;
}
int yywrap() {
return 1;
}
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
9.Lex Specification to Identify Comments
%{
#include <stdio.h>
%}
%%
"//"[^"\n"]* { printf("Comment: %s\n", yytext); } // Matches single line comments
/\*[^*]*\*+([^/*][^*]*\*+)*/ { printf("Comment: %s\n", yytext); } // Matches multiline comments
%%
int main()
{
yylex();
return 0;
}
int yywrap() {
return 1;
}
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
10.Lex Specification to Identify Real Numbers
%{
#include <stdio.h>
%}
%%
[0-9]+\.[0-9]+([eE][-+]?[0-9]+)? { printf("Real Number: %s\n", yytext); } // Matches floating point numbers with optional exponent
%%
int main()
{
yylex();
return 0;
}
int yywrap() {
return 1;
}
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

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matlex
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26 Apr-2024
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