C Program for Infix expression using Menu

#include<stdio.h>
#include<ctype.h>
#include<stdlib.h>
#define Max 20
char stOper[Max][Max], Opertop=-1;
char stOptr[Max][Max], Optrtop=-1;
int st[Max], top=-1;
void push(int ch)
{
  if (top == Max-1)
   {
      printf("Stack is full\n");
   }
   else
   {
     top++;
     st[top]=ch;
   }
}


int  pop()
{
   int ch;
     if (top==-1)
      {
 printf("Stack is empty\n");
      }
      else
      {
    ch=st[top];
    top--;
      }
      return ch;
}


void dispstack()
{
  int k;
  printf("stack Content: ");
  for (k=top; k>=0; k--)
  {
    printf("%d, ", st[k]);
  }
  printf("\n");
}


void pushOperand(char ch[25])
{
  if (Opertop == Max-1)
   {
      printf("Operand Stack is full\n");
   }
   else
   {
     Opertop++;
     strcpy(stOper[Opertop],ch);
   }
}


char* popOperand()
{
   char ch[25];
     if (Opertop==-1)
      {
 printf("Operand Stack is empty\n");
      }
      else
      {
    strcpy(ch,stOper[Opertop]);
    Opertop--;
      }
      return ch;
}


void dispOperandstack()
{
  int k;
  printf("Operand stack Content: ");
  for (k=Opertop; k>=0; k--)
  {
    printf("%s, ", stOper[k]);
  }
  printf("\n");
}


void pushOperator(char ch[25])
{
  if (Optrtop == Max-1)
   {
      printf("Operator Stack is full\n");
   }
   else
   {
     Optrtop++;
     strcpy(stOptr[Optrtop],ch);
   }
}


char* popOperator()
{
   char ch[25];
     if (Optrtop==-1)
      {
 printf("Operator Stack is empty\n");
      }
      else
      {
    strcpy(ch,stOptr[Optrtop]);
    Optrtop--;
      }
      return ch;
}


void dispOperatorstack()
{
  int k;
  printf("Operator stack Content: ");
  for (k=Optrtop; k>=0; k--)
  {
    printf("%s, ", stOptr[k]);
  }
  printf("\n");
}


int ICP(char ch)
{
  int pre,pre1;
  pre=toascii(ch);
  if (pre==43 || pre==45) pre1= 1;      /*   + and -  */
  else if (pre==42 || pre==47) pre1= 2; /*   * and /  */
  else if (pre==33)  pre1=-1;   /* !                  */
  else if (pre==40)  pre1=0;   /* Closing parenthesis ) */
  return pre1;
}


char * Prefix(char s[25])
{
  char pre[25],preOpt[25],optr[25],op1[25],op2[25];
  int i,j;
  i=0; j=0;
  Optrtop=-1;
  Opertop=-1;
  pushOperator("!");
  pushOperand("!");
  while (s[i]!='\0')
  {
     /*if operand is countered print it */
    if ( (s[i]>=97 && s[i]<=122) || (s[i]>=65 && s[i]<=90) ||(s[i]>=48 && s[i]<=57) )
    {
      j=0;
      pre[j]=s[i];
      j++;
      pre[j]='\0';
      pushOperand(pre);
    }
    else if (s[i]=='(')
    {
      pushOperator("(");
    }
    else if (s[i]==')')
    {
       while (strcmp(stOptr[Optrtop],"(")!=0)
       {
  strcpy(optr,popOperator());
  strcpy(op2, popOperand());
  strcpy(op1, popOperand());
  strcpy(pre,optr);
  strcat(pre,op1);
  strcat(pre,op2);
  pushOperand(pre);
       }
       strcpy(optr,popOperator());   /* pop closing parenthsis but don't print it */
    }
    else if ( ICP(s[i]) > ICP(stOptr[Optrtop][0]) )
    {
       j=0;
       preOpt[j]=s[i];
       j++;
       preOpt[j]='\0';
       pushOperator(preOpt);
    }
    else
    {
       do
       {
  strcpy(optr,popOperator());
  strcpy(op2,popOperand());
  strcpy(op1,popOperand());
  strcpy(pre,optr);
  strcat(pre,op1);
  strcat(pre,op2);
  pushOperand(pre);
       }
       while (ICP(s[i])<= ICP(stOptr[Optrtop][0]) );
       j=0;
       preOpt[j]=s[i];
       j++;
       preOpt[j]='\0';
       pushOperator(preOpt);
    }
    i++;
   /* dispOperatorstack();
    dispOperandstack();
    getch();  */
  }
  while ( strcmp(stOptr[Optrtop],"!")!=0 )
  {
    strcpy(optr,popOperator());
    strcpy(op2, popOperand());
    strcpy(op1, popOperand());
    strcpy(pre,optr);
    strcat(pre,op1);
    strcat(pre,op2);
    pushOperand(pre);
  }
/*  dispOperatorstack();
  dispOperandstack();*/
  strcpy(pre,popOperand());
  return pre;
}


char * Postfix(char s[25])
{
  char pos[25],posOpt[25],optr[25],op1[25],op2[25];
  int i,j;
  i=0; j=0;
  Optrtop=-1;
  Opertop=-1;
  pushOperator("!");
  pushOperand("!");
  while (s[i]!='\0')
  {
     /*if operand is countered print it */
    if ( (s[i]>=97 && s[i]<=122) || (s[i]>=65 && s[i]<=90) ||(s[i]>=48 && s[i]<=57) )
    {
      j=0;
      pos[j]=s[i];
      j++;
      pos[j]='\0';
      pushOperand(pos);
    }
    else if (s[i]=='(')
    {
      pushOperator("(");
    }
    else if (s[i]==')')
    {
       while (strcmp(stOptr[Optrtop],"(")!=0)
       {
  strcpy(optr,popOperator());
  strcpy(op2, popOperand());
  strcpy(op1, popOperand());
  strcpy(pos,op1);
  strcat(pos,op2);
  strcat(pos,optr);
  pushOperand(pos);
       }
       strcpy(optr,popOperator());   /* pop closing parenthsis but don't print it */
    }
    else if ( ICP(s[i]) > ICP(stOptr[Optrtop][0]) )
    {
       j=0;
       posOpt[j]=s[i];
       j++;
       posOpt[j]='\0';
       pushOperator(posOpt);
    }
    else
    {
       do
       {
  strcpy(optr,popOperator());
  strcpy(op2,popOperand());
  strcpy(op1,popOperand());
  strcpy(pos,op1);
  strcat(pos,op2);
  strcat(pos,optr);
  pushOperand(pos);
       }
       while (ICP(s[i])<= ICP(stOptr[Optrtop][0]) );
       j=0;
       posOpt[j]=s[i];
       j++;
       posOpt[j]='\0';
       pushOperator(posOpt);
    }
    i++;
    /*dispOperatorstack();
    dispOperandstack();
    getch(); */
  }
  while ( strcmp(stOptr[Optrtop],"!")!=0 )
  {
    strcpy(optr,popOperator());
    strcpy(op2, popOperand());
    strcpy(op1, popOperand());
    strcpy(pos,op1);
    strcat(pos,op2);
    strcat(pos,optr);
    pushOperand(pos);
  }
 /*  dispOperatorstack();
  dispOperandstack();*/
  strcpy(pos,popOperand());
  return pos;
}


int PostEval(char s[25])
{
  char temp[25];
  int i,val=0,ch1,ch2,j=0;
  i=0; top=-1;
  while (s[i]!='\0')
  {
    /*if operand is countered print it*/
    if ( (s[i]>=48 && s[i]<=57) )
    {
      j=0;
      temp[j]=s[i];
      j++;
      temp[j]='\0';
      push(atoi(temp));
    }
    else
    {
      ch1=pop();
      ch2=pop();
      switch(s[i])
      {
 case '+' :{
       val=ch2+ch1;
       break;
    }
 case '-' :{
       val=ch2-ch1;
       break;
    }
 case '*' :{
       val=ch2*ch1;
       break;
    }
 case '/' :{
       val=ch2/ch1;
       break;
    }
       }
     push(val);
    }
   i++;
  }
  val=pop();
  return val;
}


int PreEval(char s[25])
{
  char temp[25];
  int i,val=0,ch1,ch2,j=0;
  i=0; top=-1;
  while (s[i]!='\0')
  {
    /*if operand is countered print it*/
    if ( (s[i]>=48 && s[i]<=57) )
    {
      j=0;
      temp[j]=s[i];
      j++;
      temp[j]='\0';
      push(atoi(temp));
    }
    else
    {
      ch2=pop();
      ch1=pop();
      switch(s[i])
      {
 case '+' :{
       val=ch2+ch1;
       break;
    }
 case '-' :{
       val=ch2-ch1;
       break;
    }
 case '*' :{
       val=ch2*ch1;
       break;
    }
 case '/' :{
       val=ch2/ch1;
       break;
    }
       }
     push(val);
    }
   i++;
  }
  val=pop();
  return val;
}



char* PosttoInfix(char s[25])
{
  char ifx[25],ch1[25],ch2[25],ch3[25];
  int i,j;
  i=0; j=0; Opertop=-1;
  while (s[i]!='\0')
  {
    /*if operand is countered print it */
    if ( (s[i]>=97 && s[i]<=122) || (s[i]>=65 && s[i]<=90) || (s[i]>=48 && s[i]<=57) )
    {
      j=0;
      ifx[j]=s[i];
      j++;
      ifx[j]='\0';
      pushOperand(ifx);
    }
    else
    {
      strcpy(ch1,popOperand());
      strcpy(ch2,popOperand());
      j=0;
      ch3[j]=s[i];
      j++;
      ch3[j]='\0';
      strcpy(ifx,"(");
      strcat(ifx,ch2);
      strcat(ifx,ch3);
      strcat(ifx,ch1);
      strcat(ifx,")");
      pushOperand(ifx);
    }
    i++;
  }
  return popOperand();
}



char* PretoInfix(char s[25])
{
  char ifx[25],ch1[25],ch2[25],ch3[25];
  int i,j;
  i=0; j=0; Opertop=-1;
  while (s[i]!='\0')
  {
    /*if operand is countered print it */
    /*printf("s=%c\n",s[i]);*/
    if ( (s[i]>=97 && s[i]<=122) || (s[i]>=65 && s[i]<=90) || (s[i]>=48 && s[i]<=57) )
    {
      j=0;
      ifx[j]=s[i];
      j++;
      ifx[j]='\0';
      pushOperand(ifx);
    }
    else
    {
      strcpy(ch1,popOperand());
      strcpy(ch2,popOperand());
      j=0;
      ch3[j]=s[i];
      j++;
      ch3[j]='\0';
      strcpy(ifx,ch1);
      strcat(ifx,ch3);
      strcat(ifx,ch2);
      pushOperand(ifx);
    }
    i++;
  }
  return popOperand();
}



void main()
{
  char s[25],pre[25],pos[25],PtoInf[25],PrtoInf[25],prerev[25];
  int val,choice;
  while(1)
  {
     clrscr();
     printf("1. Infix to Postfix Expression\n");
     printf("2. Infix to Prefix Expression \n");
     printf("3. Postfix to Infix Expression \n");
     printf("4. Prefix to Infix Expression \n");
     printf("5. Evaluation of Postfix Expression \n");
     printf("6. Evaluation of Prefix Expression \n");
     printf("7. Exit\n");
     printf("Enter Choice : ");
     scanf("%d",&choice);
     switch(choice)
     {
  case 1: {
    printf("Enter Infix Expression\n");
    scanf("%s",s);
    strcpy(pre,Postfix(s));
    printf("Postfix Expression = %s\n", pre);
    break;
   }
  case 2: {
    printf("Enter Infix Expression\n");
    scanf("%s",s);
    strcpy(pre,Prefix(s));
    printf("Prefix Expression = %s\n", pre);
    break;
   }
  case 3: {
    printf("Enter Postfix Expression\n");
    scanf("%s",s);
    strcpy(PtoInf,PosttoInfix(s));
    printf("Postfix to Infix =%s\n", PtoInf);
    break;
   }
  case 4: {
    printf("Enter prefix Expression\n");
    scanf("%s",s);
    strcpy(prerev, strrev(s));
    strcpy(PrtoInf,PretoInfix(prerev));
    printf("Prefix to Infix =%s\n", PrtoInf);
    break;
   }
  case 5: {
    printf("Enter Postfix Expression\n");
    scanf("%s",s);
    val= PostEval(s);
    printf("Value of Postfix Expression=%d\n", val);
    break;
   }
  case 6: {
    printf("Enter Prefix Expression\n");
    scanf("%s",s);
    strcpy(prerev,strrev(s));
    val=PreEval(prerev);
    printf("Value of Prefix Expression = %d\n", val);
    break;
   }
  case 7: {
    exit(0);
   }
     }
     getch();
  }
}