lex program to count the number of fraction Positive and negative integer

/* decleration section in this sections we will decleared the different value and include the header file which we are using in this program to run this program */
%{
#include<stdio.h>
int pf_count=0;
int nf_count=0;
%}

/* this sections is known as defined section in which we defined the rule and regulation of regular expression which will going to accept or not */

%%
[+]?([0-9])+(\.([0-9])+)? {

/* this is for fraction as eg: 2.03, +1 ,+0.3*/

pf_count++; printf("Positive fraction Integer:%s\n",yytext);}

[-]([0-9])+(\.([0-9]+))? {

/* this will accept the negative fraction as eg: -3.3,-6 */

nf_count++; printf("Negative fraction Integer:%s\n",yytext);}

%%

/* main function for calling the function */

void main(int argc[],char *argv[])
{
yylex();
printf("the total number of Postive Integer are: %d\n" ,pf_count);
printf("the total number of Negative Integer are:%d\n",nf_count);
}

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run this program we need to do some steps as follows

1 step- save as .l extension and run "flex filename.l "
2 step- there would be a c program generated by flex analyser which may be "lex.yy.c" run this file as this command "gcc lex.yy.c -o first -ll" or "cc lex.yy.c -o first -ll"

3rd step- for output "./a.out " and enter the input after complete input press ctrl + D so that input sections will complete ,it will display the result

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YACC Program to check whether the arithmetic expression is valid or not

validexp.l //LEX Program /* declaration section in this sections we will declare the different value and include the header file which we are using in this program to run this program */ %{ #include"y.tab.h" extern yylval; %} /* defined section */ %% [0-9]+ {yylval=atoi(yytext); return NUMBER;} //this is send to the yacc code as token INTEGER [a-zA-Z]+ {return ID;} //this is send to the yacc code as token ID [\t]+ ; \n {return 0;} . {return yytext[0];} %% validexp.y //yacc program //decelration section %{ #include<stdio.h> %} //definition section %token NUMBER ID // token from lex file %left '+' '-' ...

LEX to count the no of "scanf" and "printf" statement in a c program. Replace them with "writf" and "readf" respectively.

/* declaration section in this sections we will declare the different value and include the header file which we are using in this program to run this program */ %{ #include<stdio.h> int sf=0,pf=0; %} /* defined section */ %% "scanf" { sf++; fprintf(yyout,"readf");} // replace scanf with readf "printf" { pf++; fprintf(yyout,"writef");} // replace printf with writef %% int main() { yyin=fopen("open.c","r"); // input file open.c yyout=fopen("new.c","w"); // output file new.c with replace yylex(); //no of printf and scanf in the file printf("Number of scanfs=%d\nNumber of Printf's=%d\n",sf,pf); return 0; } download the file ...

lex program to count the number of Positive and negative integer

/* decleration section in this sections we will decleared the different value and include the header file which we are using in this program to run this program */ %{ #include<stdio.h> int p_count=0; int n_count=0; %} /* this sections is known as defined section in which we defined the rule and regulation of regular expression which will going to accept or not */ %% [+]?([0-9])+ { /* this is for increment and print the positive integer eg: 96, +36 */ p_count++; printf("Positive Integer:%s\n",yytext);} [-]([0-9])+ { /* this is for increment and print the negative integer eg: -96, -36 */ n_count++; printf("negative Integer:%s\n",yytext);} %% /* main function for calling the function */ void main(int argc[],char *argv[]) { yylex(); printf("the total number of Postive Integer are: %d\n" ,p_count); printf("the total number of Negative Integer are:%d\n",n_count); } ...

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