Lab Programs

%{
#include<stdio.h>
int v=0,op=0,id=0,flag=0;
%}
%%
[0-9][0-9]* {id++;printf("\nIdentifier:");ECHO;}
[\+\-\*\/\=] {op++;printf("\nOperartor:");ECHO;}
"(" {v++;}
")" {v--;}
";" {flag=1;}
.|\n {return 0;}
%%
int main()
{
printf("Enter the expression:\n");
yylex();
if((op+1) ==id && v==0 && flag==0)
{
printf("\n\nIdentifiers are:%d\nOperators are:%d\n",id,op);
printf("\nExpression is Valid\n");
}
else
printf("\nExpression is Invalid\n");
return 1;
}
int yywrap()
{
return 1;
}

Lex Part
%{
#include "y.tab.h"
extern int yylval;
%}
%%
[0-9]+ {yylval=atoi(yytext);return num;}
[\+\-\*\/] {return yytext[0];}
[)] {return yytext[0];}
[(] {return yytext[0];}
. {;}
\n {return 0;}
%%
yacc part
%{
#include<stdio.h>
#include<stdlib.h>
int yylex();
int yylval;
int yyerror();
%}
%token num
%left '+' '-'
%left '*' '/'
%%
input:exp {printf("%d\n",$$);exit(0);}
exp: exp'+'exp {$$=$1+$3;}
|exp'-'exp {$$=$1-$3;}
|exp''exp {$$=$1$3;}
|exp'/'exp
{ if($3==0){
printf("Divide by Zero. Invalid expression.\n");
exit(0);
}
else
{$$=$1/$3;}}
|'('exp')' {$$=$2;}
|num {$$=$1;};
%%
int yyerror()
{
printf("Error. Invalid Expression.\n");
exit(0);
}
int main()
{
printf("Enter an expression:\n");
yyparse();
}

PROGRAM 1

PROGRAM 2

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

char prod[3][10] = {"A->aBa", "B->bB", "B->@"};
char input[10], stack[25];
int top = -1;
int j = 0, k, l;

void push(char item)
{
    stack[++top] = item;
}

void pop()
{
    top = top - 1;
}

void display()
{
    int j;
    for (j = top; j >= 0; j--)
    {
        printf("%c", stack[j]);
    }
}

void stackpush(char p)
{
    if (p == 'A')
    {
        pop();
        for (j = strlen(prod[0]) - 1; j >= 3; j--)
            push(prod[0][j]);
    }
    else
    {
        pop();
        for (j = strlen(prod[1]) - 1; j >= 3; j--)
            push(prod[1][j]);
    }
}

int main()
{
    char c;
    int i;
    printf("first(A)={a}\t");
    printf("follow(A)={$}\n");
    printf("first(B)={b,@}\t");
    printf("follow(B)={a}\n\n");

printf("\t a \t b \t $ \n");
    printf("A \t%s\n", prod[0]);
    printf("B\t%s\t%s\n", prod[2], prod[1]);
    printf("Enter the input string terminated with $ to parse: ");
    scanf("%s", input);

for (i = 0; input[i] != '\0'; i++)
    {
        if ((input[i] != 'a') && (input[i] != '$') && (input[i] != 'b'))
        {
            printf("Invalid string\n");
            exit(0);
        }
    }

if (input[i - 1] != '$')
    {
        printf("\nInput string entered without end marker $\n");
        exit(0);
    }

push('$');
    push('A');

printf("\n\nstack\tInput\ttransaction");
    printf("\n---------------------------\n");

i = 0;  // Resetting the input string index to 0

while (i <= strlen(input) && stack[top] != '$')
    {
        printf("\n");
        display();
        printf("\t");
        for (l = i; l < strlen(input); l++)
            printf("%c", input[l]);
        printf("\t");

if (stack[top] == 'A')
        {
            printf("A->aBa");
            stackpush('A');
        }
        else if (stack[top] == 'B')
        {
            if (input[i] != 'b')
            {
                printf("B->@");
                printf("\t matched @");
                pop();
            }
            else
            {
                printf("B->bB");
                stackpush('B');
            }
        }
        else
        {
            if (stack[top] == input[i])
            {
                printf("pop %c", input[i]);
                printf("\tmatched %c", input[i]);
                pop();
                i++;
            }
            else
                break;
        }
    }

if (stack[top] == '$' && input[i] == '$')
    {
        printf("\n$\t$");
        printf("\nValid String Accepted\n");
    }
    else
        printf("\nInvalid string rejected \n");

return 0;
}

PROGRAM 3

#include<stdio.h>
          #include<string.h>
          #include<stdlib.h>
          int k=0,z=0,i=0,j=0,c=0;
          char a[16],ac[20],stk[15],act[10];
          void check();
          void main()
          {
          puts("GRAMMAR is E->E+E \n E->E*E \n E->(E) \n E->id");
          puts("enter input string ");
          gets(a);
          c=strlen(a);
          strcpy(act,"SHIFT->");
          puts("stack \t input \t action");
          for(k=0,i=0; j<c; k++,i++,j++)
          {
          if(a[j]=='i' && a[j+1]=='d')
          {
          stk[i]=a[j];
          stk[i+1]=a[j+1];
          stk[i+2]='\0';
          a[j]=' ';
          a[j+1]=' ';
          printf("\n$%s\t%s$\t%sid",stk,a,act);
          check();
          }
          else
          {
          stk[i]=a[j];
          stk[i+1]='\0';
          a[j]=' ';
          printf("\n$%s\t%s$\t%ssymbols",stk,a,act);
          check();
          }
          }
          }
          void check()
          {
          strcpy(ac,"REDUCE TO E");
          for(z=0; z<c; z++)
          if(stk[z]=='i' && stk[z+1]=='d')
          {
          stk[z]='E';
          stk[z+1]='\0';
          printf("\n$%s\t%s$\t%s",stk,a,ac);
          j++;
          }
          for(z=0; z<c; z++)
          if(stk[z]=='E' && stk[z+1]=='+' && stk[z+2]=='E')
          {
          stk[z]='E';
          stk[z+1]='\0';
          stk[z+2]='\0';
          printf("\n$%s\t%s$\t%s",stk,a,ac);
          i=i-2;
          }
          for(z=0; z<c; z++)
          if(stk[z]=='E' && stk[z+1]=='*' && stk[z+2]=='E')
          {
          stk[z]='E';
          stk[z+1]='\0';
          stk[z+1]='\0';
          printf("\n$%s\t%s$\t%s",stk,a,ac);
          i=i-2;
          }
          for(z=0; z<c; z++)
          if(stk[z]=='(' && stk[z+1]=='E' && stk[z+2]==')')
          {
          stk[z]='E';
          stk[z+1]='\0';
          stk[z+1]='\0';
          printf("\n$%s\t%s$\t%s",stk,a,ac);
          i=i-2;
          }
          }

PROGRAM 4

#include<stdio.h>
          #include<stdlib.h>
          #include<ctype.h>
          #include<string.h>
          char op[2],arg1[5],arg2[5],result[5];
          void main()
          {
          FILE *fp1,*fp2;
          fp1=fopen("input.txt","r");
          fp2=fopen("output.txt","w");
          while(!feof(fp1))
          {
          fscanf(fp1,"%s%s%s%s",result,arg1,op,arg2);
          if(strcmp(op,"+")==0)
          {
          fprintf(fp2,"\nMOV R0,%s",arg1);
          fprintf(fp2,"\nADD R0,%s",arg2);
          fprintf(fp2,"\nMOV %s,R0",result);
          }
          if(strcmp(op,"*")==0)
          {
          fprintf(fp2,"\nMOV R0,%s",arg1);
          fprintf(fp2,"\nMUL R0,%s",arg2);
          fprintf(fp2,"\nMOV %s,R0",result);
          }
          if(strcmp(op,"-")==0)
          {
          fprintf(fp2,"\nMOV R0,%s",arg1);
          fprintf(fp2,"\nSUB R0,%s",arg2);
          fprintf(fp2,"\nMOV %s,R0",result);
          }
          if(strcmp(op,"/")==0)
          {
          fprintf(fp2,"\nMOV R0,%s",arg1);
          fprintf(fp2,"\nDIV R0,%s",arg2);
          fprintf(fp2,"\nMOV %s,R0",result);
          }
          if(strcmp(op,"=")==0)
          {
          fprintf(fp2,"\nMOV R0,%s",arg1);
          fprintf(fp2,"\nMOV %s,R0",result);
          }
          }
          fclose(fp1);
          fclose(fp2);
          }

//input.txt
          T1 -B = ?
          T2 C+D
          T3 T1+T2
          A T3 = ?

PROGRAM 5

%{
              #include<stdio.h>
              int sl=0;
              int ml=0;
              %}
              %%
              "/*"[a-zA-Z0-9' '\t\n]+"*/" ml++;
              "//".* sl++;
              %%
              int main()
              {
              yyin=fopen("f1.c","r");
              yyout=fopen("f2.c","w");
              yylex();
              fclose(yyin);
              fclose(yyout);
              printf("\n Number of single line comments are =%d\n",sl);
              printf("\nNumber of multiline comments are=%d\n",ml);
              return 0;
              }

//test progrqm
              #include<stdio.h>
              int main()
              {
              /*abcd
              sbbnd
              bbsg*/
              printf("hello");
              printf("world");
              return 0;
              }

lex 6a.l
              gcc lex.yy.c -ll
              ./a.out
           
              Number of single line comments are =1
              Number of multiline comments are=1

%{
                        #include <stdio.h>
                        #include "y.tab.h"
                        extern int yylval;
                        %}
                        %%
                        [ \t];
                        [+|-|*|/|=|<|>] {printf("operator is %s\n",yytext);return OP;}
                        [0-9]+ {yylval = atoi(yytext); printf("numbers is %d\n",yylval); return DIGIT;}
                        int|char|bool|float|void|for|do|while|if|else|return|void {printf("keyword is %s\n",yytext);return KEY;}
                        [a-zA-Z0-9]+ {printf("identifier is %s\n",yytext);return ID;}
                        . ;
                        %%

%{
                      #include<stdio.h>
                  #include<stdlib.h>
                  int yyerror();
                  int yylex();
                  int id=0, dig=0, key=0, op=0;
                  %}
                  %token DIGIT ID KEY OP
                  %%
                  input:
                  DIGIT input { dig++; }
                  | ID input { id++; }
                  | KEY input { key++; }
                  | OP input {op++;}
                  | DIGIT { dig++; }
                  | ID { id++; }
                  | KEY { key++; }
                  | OP { op++;}
                  ;
                  %%
                  #include<stdio.h>
                  int yyparse();
                  extern FILE *yyin;
                  int main() {
                  FILE *myfile = fopen("a.c","r");
                  if (!myfile)
                  {
                  printf("I can't open sam_input.c!");
                  return -1;
                  }
                  yyin = myfile;
                  do {
                  yyparse();
                  }while (!feof(yyin));
                  printf("numbers = %d\nKeywords = %d\nIdentifiers = %d\noperators =%d\n",dig, key,id, op);
                  return 1;
                  }
                  int yyerror()
                  {
                  printf("EEK, parse error! Message: ");
                  exit(-1);
                  }

void main()
                  {
                  int a;
                  float bc;
                  char c;
                  char ch;
                  if(a==80)
                  printf("good");
                  else
                  printf("bad");
                  }

lex 6b.l
                  yacc -d 6b.y
                  gcc lex.yy.c y.tab.c -ll 
                  ./a.out

keyword is void
                  identifier is main
                  
                  
                  keyword is int
                  identifier is a
                  
                  keyword is float
                  identifier is bc
                  
                  keyword is char
                  identifier is c
                  
                  keyword is char
                  identifier is ch
                  
                  keyword is if
                  identifier is a
                  operator is =
                  operator is =
                  numbers is 80
                  
                  identifier is printf
                  identifier is good
                  
                  keyword is else
                  
                  identifier is printf
                  identifier is bad
                  
                  numbers = 1
                  Keywords = 7
                  Identifiers = 10
                  operators =2

PROGRAM 6

#include<stdio.h>
          #include<stdlib.h>
          struct proc
          {
          int id;
          int arrival;
          int burst;
          int rem;
          int wait;
          int finish;
          int turnaround;
          float ratio;
          }
          process[10];
          struct proc temp;
          int no;
          int chkprocess(int);
          int nextprocess();
          void roundrobin(int, int, int[], int[]);
          void srtf(int);
          int main()
          {
          int n,tq,choice;
          int bt[10],st[10],i,j,k;
          for(; ;)
          {
          printf("Enter the choice \n");
          printf(" 1. Round Robin\n 2. SRT\n 3. Exit \n");
          scanf("%d",&choice);
          switch(choice)
          {
          case 1:
          printf("Round Robin scheduling algorithm\n");
          printf("Enter number of processes:\n");
          scanf("%d",&n);
          printf("Enter burst time for sequences:");
          for(i=0;i<n;i++)
          {
          scanf("%d",&bt[i]);
          st[i]=bt[i];
          }
          printf("Enter time quantum:");
          scanf("%d",&tq);
          roundrobin(n,tq,st,bt);
          break;
          case 2:
          printf("\n \n ---SHORTEST REMAINING TIME NEXT---\n \n ");
          printf("\n \n Enter the number of processes: ");
          scanf("%d", &n);
          srtf(n);
          break;
          case 3: exit(0);
          }
          }
          }
          void roundrobin(int n,int tq,int st[],int bt[])
          {
          int time=0;
          int tat[10],wt[10],i,count=0,swt=0,stat=0,temp1,sq=0,j,k;
          float awt=0.0,atat=0.0;
          while(1)
          {
          for(i=0,count=0;i<n;i++)
          {
          temp1=tq;
          if(st[i]==0)
          {
          count++;
          continue;
          }
          if(st[i]>tq)
           
          st[i]=st[i]-tq;
          else
          if(st[i]>=0)
          {
          temp1=st[i];
          st[i]=0;
          }
          sq=sq+temp1;
           
          tat[i]=sq;
          }
          if(n==count)
          break;
          }
          for(i=0;i<n;i++)
          {
          wt[i]=tat[i]-bt[i];
          swt=swt+wt[i];
          stat=stat+tat[i];
          }
          awt=(float)swt/n;
          atat=(float)stat/n;
          printf("Process_no Burst time Wait time Turn around time\n");
          for(i=0;i<n;i++)
          printf("%d\t\t%d\t\t%d\t\t%d\n",i+1,bt[i],wt[i],tat[i]);
          printf("Avg wait time is %f\n Avg turn around time is %f\n",awt,atat);
          }
          int chkprocess(int s)
          {
          int i;
          for(i = 1; i <= s; i++)
          {
          if(process[i].rem != 0)
          return 1;
          }
          return 0;
          }
          int nextprocess()
          {
          int min, l, i;
          min = 32000;
          for(i = 1; i <= no; i++)
          {
          if( process[i].rem!=0 && process[i].rem < min)
          {
          min = process[i].rem;
          l = i;
          }
          }
          return l;
          }
          void srtf(int n)
          {
          int i,j,k,time=0;
          float tavg,wavg;
          for(i = 1; i <= n; i++)
          {
          process[i].id = i;
          printf("\n\nEnter the arrival time for process %d: ", i);
          scanf("%d", &(process[i].arrival));
          printf("Enter the burst time for process %d: ", i);
          scanf("%d", &(process[i].burst));
          process[i].rem = process[i].burst;
          }
          for(i = 1; i <= n; i++)
          {
          for(j = i + 1; j <= n; j++)
          {
           
          if(process[i].arrival > process[j].arrival)
          {
          temp = process[i];
          process[i] = process[j];
          process[j] = temp;
          }
          }
          }
          no = 0;
          j = 1;
          while(chkprocess(n) == 1)
          {
          if(process[no + 1].arrival == time)
          {
          while(process[no+1].arrival==time)
          no++;
          if(process[j].rem==0)
          process[j].finish=time;
          j = nextprocess();
          }
          if(process[j].rem != 0)
          {
          process[j].rem--;
          for(i = 1; i <= no; i++)
          {
          if(i != j && process[i].rem != 0)
          process[i].wait++;
          }
          }
          else
          {
          process[j].finish = time;
          j=nextprocess();
          time--;
          k=j;
          }
          time++;
          }
          process[k].finish = time;
          printf("\n\n\t\t\t---SHORTEST REMAINING TIME FIRST---");
          printf("\n\n Process Arrival Burst Waiting Finishing turnaround Tr/Tb\n");
          printf("%5s %9s %7s %10s %8s %9s\n\n", "id", "time", "time", "time", "time", "time");
          for(i = 1; i <= n; i++)
          {
          process[i].turnaround = process[i].wait + process[i].burst;
          printf("%5d %8d %7d %8d %10d %9d %10.1f ", process[i].id,
          process[i].arrival, process[i].burst, process[i].wait, process[i].finish,
          process[i].turnaround, process[i].ratio);
          tavg=tavg+ process[i].turnaround;
           
          wavg=wavg+process[i].wait;
           
          printf("\n\n");
          }
          tavg=tavg/n;
          wavg=wavg/n;
          printf("tavg=%f\t wavg=%f\n",tavg,wavg);
           }

PROGRAM 7

#include <stdio.h>
          #include <stdlib.h>
          
          int main()
          {
          int Max[10][10], need[10][10], alloc[10][10], avail[10], completed[10], safeSequence[10];
          int p, r, i, j, process, count;
          count = 0;
          printf("Enter the no of processes : ");
          scanf("%d", &p);
          for(i = 0; i< p; i++)
          completed[i] = 0;
          printf("Enter the no of resources : ");
          scanf("%d", &r);
          printf("Enter the Max Matrix for each process : ");
          for(i = 0; i < p; i++)
          {
          printf("\nFor process %d : ", i + 1);
          for(j = 0; j < r; j++)
          scanf("%d", &Max[i][j]);
          }
          printf("Enter the allocation for each process : ");
          for(i = 0; i < p; i++)
          {
          printf("\nFor process %d : ",i + 1);
          for(j = 0; j < r; j++)
          scanf("%d", &alloc[i][j]);
          }
          printf("Enter the Available Resources : ");
          for(i = 0; i < r; i++)
          scanf("%d", &avail[i]);
          for(i = 0; i < p; i++)
          for(j = 0; j < r; j++)
          need[i][j] = Max[i][j] - alloc[i][j];
          do
          {
          printf("Max matrix:\t\nAllocation matrix:\n");
          for(i = 0; i < p; i++)
          {
          for( j = 0; j < r; j++)
          printf("%d ", Max[i][j]);
          printf("\t\t");
          for( j = 0; j < r; j++)
          printf("%d ", alloc[i][j]);
          printf("\n");
          }
          process = -1;
          for(i = 0; i < p; i++)
          {
          if(completed[i] == 0)//if not completed
          {
          process = i ;
          for(j = 0; j < r; j++)
          {
          if(avail[j] < need[i][j])
          {
          process = -1;
          break;
          }
          }
          }
          if(process != -1)
          break;
          }
          if(process != -1)
          {
          printf("Process %d runs to completion!", process + 1);
          safeSequence[count] = process + 1;
          count++;
          for(j = 0; j < r; j++)
          {
          avail[j] += alloc[process][j];
          alloc[process][j] = 0;
          Max[process][j] = 0;
          completed[process] = 1;
          }
          }
          }
          while(count != p && process != -1);
          if(count == p)
          {
          printf("The system is in a safe state!!\n");
          printf("Safe Sequence : < ");
          for( i = 0; i < p; i++)
          printf("%d ", safeSequence[i]);
          printf(">\n");
          }
          else
          printf("The system is in an unsafe state!!");
          }

PROGRAM 8

#include<stdio.h>
#include<stdlib.h>
void FIFO(char [ ],char [ ],int,int);
void lru(char [ ],char [ ],int,int);
void opt(char [ ],char [ ],int,int);
int main()
{
int ch,YN=1,i,l,f;
char F[10],s[25];
printf("\n\n\tEnter the no of empty frames: ");
scanf("%d",&f);
printf("\n\n\tEnter the length of the string: ");
scanf("%d",&l);
printf("\n\n\tEnter the string: ");
scanf("%s",s);
for(i=0;i<f;i++)
F[i]=-1;
do
{
printf("\n\n\t*********** MENU ***********");
printf("\n\n\t1:FIFO\n\n\t2:LRU \n\n\t3:EXIT");
printf("\n\n\tEnter your choice: ");
scanf("%d",&ch);
switch(ch)
{
case 1:
for(i=0;i<f;i++)
{
F[i]=-1;
}
FIFO(s,F,l,f);
break;
case 2:
for(i=0;i<f;i++)
{
F[i]=-1;
}
lru(s,F,l,f);
break;
case 3:
exit(0);
}
printf("\n\n\tDo u want to continue IF YES PRESS 1\n\n\tIF NO PRESS 0 : ");
scanf("%d",&YN);
}while(YN==1);
return(0);
}
//FIFO
void FIFO(char s[],char F[],int l,int f)
{
int i,j=0,k,flag=0,cnt=0;
printf("\n\tPAGE\t FRAMES\t FAULTS");
for(i=0;i<l;i++)
{
for(k=0;k<f;k++)
{
if(F[k]==s[i])
flag=1;
}
if(flag==0)
{
printf("\n\t%c\t",s[i]);
F[j]=s[i];
j++;
for(k=0;k<f;k++)
{
printf(" %c",F[k]);
}
printf("\tPage-fault%d",cnt);
cnt++;
}
else
{
flag=0;
printf("\n\t%c\t",s[i]);
for(k=0;k<f;k++)
{
printf(" %c",F[k]);
}
printf("\tNo page-fault");
}
if(j==f)
j=0;
}
}
//LRU
void lru(char s[],char F[],int l,int f)
{
int i,j=0,k,m,flag=0,cnt=0,top=0;
printf("\n\tPAGE\t FRAMES\t FAULTS");
for(i=0;i<l;i++)
{
for(k=0;k<f;k++)
{
if(F[k]==s[i])
{
flag=1;
break;
}
}
printf("\n\t%c\t",s[i]);
if(j!=f && flag!=1)
{
F[top]=s[i];
j++;
if(j!=f)
top++;
}
else
{
if(flag!=1)
{
for(k=0;k<top;k++)
{
F[k]=F[k+1];
}
F[top]=s[i];
}
if(flag==1)
{
for(m=k;m<top;m++)
{
F[m]=F[m+1];
}
F[top]=s[i];
}
}
for(k=0;k<f;k++)
{
printf(" %c",F[k]);
}
if(flag==0)
{
printf("\tPage-fault%d",cnt);
cnt++;
}
else
printf("\tNo page fault");
flag=0;
}
}