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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); }                ...