Algorithm:-
begin
if a,e,I,o,u or A,E,I,O,U
then
printf “It is a vowel”
else
printf “It is a consonant”
end

1. LEX program to count number of vowels and consonants in a given input string

%%
{printf(“it is vowel”);}
{printf(“it is consonant”);}
%%
main()
{
yylex();
}
int yywrap()
{
return 1;
}


Output:

$./a.out
a
it is a vowel
g
it is a consonant
..............etc

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..............etc

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Objective
Program in “LEX” to count number of Characters, Words, Lines.

%{
int nchar=0,nword=0,nline=0;
#include
%}
%%
\n {nline++;nchar++;}
+ {nword++;nchar+=yyleng;}
. {nchar++;}
%%
int main()
{
yylex();
printf(%d%d%d,nchar,nword,nline);
}
..............etc

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Objective
Program in “LEX” to count number of Identifiers and Keywords.

digit
letter
%{
int count1=0;
int count2=0;
%}
%%
intI
floatI
char {count++;printf(%s is keyword,yytext);}
{letter}I({letter}I{digit})*{count2++;}
+ {printf(%s is not keyword,yytext);}
.I\n {ECHO;}
%%
main()
{
yylex();
printf(%d no of keyword %d no of id,count1,count2);
}
..............etc

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Objective
Program to count the number of identifiers in a c file
Program:

%{
#include
int id=0, i;
%}
%%
int ||
float ||
double ||
char ||
bool {
i = 0;
while (yytext != ';')
{
if(yytext == ',')
id++;
i++;
}
..............etc

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Algorithm:-

begin
if string=*000*
then
printf “Algorithm:-

string accepted”
else
printf “string rejected”
end

Program:-

LEX program to recognize a string with three consecutive 0’s

%%
*000* { printf(“string accepted”);}
* { printf(“string rejected”);}

%%

main()
{
yylex();
}\
int yywrap()
{
return 1;
}
..............etc

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Objective
Program in “C/Lex” to check whether Identifier is valid or not
#include
#include
void main()
{
clrscr();
int i=0,j=0,flag=1;
char ch,ip;
while((ch=getchar())!='\n')
{
ip=ch;
i++;
}
ip='*';
if((ip>='a'&&ip<='z')||(ip>='A'&&ip<='Z'))
{
j++;
while(ip!='*')
{
if((ip>='a'&&ip<='z')||(ip>='A'&&ip<='Z')||(ip>='0'&&ip<='9')||ip=='_')
{
j++;
}
else
{
flag=0;
goto loop;
}
}
}
else
flag=0;
lo..............etc

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Objective
Program in “LEX” to count number of vowels and consonants .

%{
int count1=0;
int count2=0;
%}
%%
aIeIiIoIu {printf(%s is vowel,yytext);count1++;}
{printf(%s is constonant,yytext);count2++;}
.I\n {ECHO;}
%%
main()
{
yylex();
printf(%d Vowel =%d constonant=,count1,count2);
}
..............etc

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Objective
Program in “LEX” to count the verb in a given line of text.

%{
%}
%%
isI
areI
amI printf(%s is verb,yytext );
+ {printf(%s is not a verb,yytext);}
.I\n {ECHO;}
%%
main()
{
yylex();
}
..............etc

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lex program to recognise and count number of identifiers in a given file ?..............etc

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