// Majdal AL Hindi
//1071842
//project #2



// this project read equations from file and check if there are
//errors in the equations,convert the equation from infix to postfix expression
//and evaluate the value , finally its save the equation and
// the conversion form and the value in output file








#include<stdio.h>
#include<conio.h>
#include<string.h>
#define MAX 20


// strucuture to bulid the stack

typedef struct
{
int a[100];
int top;

}STACK;


// push function to put the value in the stack


void push(STACK *s,int x)


    {
        if(s->top==99)
        printf("STACK OVERFLOW\n");
        else
        s->a[++s->top]=x;
    }


// pop function to remove value from the stack


    int pop(STACK *s)
{
        int x;
        if(s->top<0)
        printf("STACK UNDERFLOW\n");
        else
    {
        x=s->a[s->top--];
        return x;
    }
}

// operation function to evaluate the last two value in the stack

int operation(int operand1,int operand2,char operatr)
{
   switch(operatr)
{
    case '+':return operand1+operand2;
    case '*':return operand1*operand2;
    case '-':return operand1-operand2;
    case '/':return operand1/operand2;
}

}


// function to calculate the value of the postfix expression

int evaluate(char postfix[])
{

    STACK s1;
    int p1,p2,result,i;
    s1.top=-1;

    for(i=0;postfix[i]!='\0';i++)
        if(isdigit(postfix[i]))
            push(&s1,postfix[i]-'0');
        else

    {
        p2=pop(&s1);
        p1=pop(&s1);
        result=operation(p1,p2,postfix[i]);
        push(&s1,result);
    }
        return pop(&s1);
}



char stack[MAX];
int top1=-1;
char pop1();
void push1(char item);


// function to check which operator has a high precedence to evaluate

int precdence (char symbol)
{
    switch(symbol)
{
    case '+':
    case '-':return 2;
    break;
    case '*':
    case '/':return 4;
    break;
    case '^':return 6;
    break;
    case '(':
    case ')':
    case '#':return 1;
    break;
}

}


// function to check if the current operator is one of these operators

int isoperator(char symbol)
{
  switch(symbol)
{

case '+':
case '-':
case '*':
case '/':
case '^':
case '(':
case ')':return 1;
break;
default:return 0;

}

}

// function to convert from infix to postfix  expression

void convert(char infix[],char postfix[])

{


int i,symbol,j=0;
stack[++top1]='#';


  for(i=0;i<strlen(infix);i++)
{
   symbol=infix[i];
  if(isoperator(symbol)==0)

{
   postfix[j]=symbol;
   j++;
}
else{

if(symbol=='(')
push1(symbol);
else if(symbol==')')

{
while(stack[top1]!='(')
{
postfix[j]=pop1();
j++;

}
pop1();
}

else

{

if( precdence (symbol)> precdence (stack[top1]))
push1(symbol);
else
{

while( precdence (symbol)<= precdence (stack[top1]))

{
  postfix[j]=pop1();
  j++;
}
  push1(symbol);

   }
  }
 }
}


while(stack[top1]!='#')

{
postfix[j]=pop1();
j++;
}

postfix[j]='\0';
printf("%s\n",postfix);


}




void push1(char item)
{
top1++;
stack[top1]=item;
}



char pop1()
{
char a;
a=stack[top1];
top1--;

return a;
}




int menu()

    {
    int i ;

    do{
    printf("\t\t\t\t  *********");
    printf("\n\t\t\t  **************************");
    printf("\n\t***************************  MENU  ***************************\n\n\n");
    printf("\t\t\t  1 - Read Data from file\n \n");
    printf("\t\t\t  2-  Compile\n\n");
    printf("\t\t\t  3 - Exit\n");
    printf("\nSelect number :");
    scanf("%d",&i);

    }while((i != 1)&&(i != 2)&&(i != 3));

    return (i);
}




// function to read data from the file

void read_data(FILE *in,char infix[][80])

{

          int i = 0;

        printf(" \n\n\tThe data in the file: \n\n");
        char temp[200];
        while(fgets(temp,200,in)!= NULL)

        {
            strcpy(infix[i],temp);
            printf("%s\n",infix[i]);
            i++;

        }

}


//function to check if there is an error in the equations

int compile(char infix[])

{
    int i ;
    for(i=0;i<strlen(infix)-1;i++)

// check if two operators are together

        if(isoperator(infix[i]) && isoperator(infix[i+1]))
        {
            printf("\nthere are two operators together so : \n");
            return 1 ;
        }

// check if there  is an open parantheses

    i = 0;
    int flag = 0 ;
    int j = 0 ;
    for(i=0;i<strlen(infix);i++)
    {
        if(infix[i]=='('){
            flag = 1 ;
            j=i;
        }
        if((infix[i]==')')&&(i>j))
            flag = 0;
    }
    if(flag){
    printf("open  parntheses\n");
    return 1 ;
    }
    i = 0 ;
    for(i=0;i<strlen(infix);i++){
       if((infix[i]=='(')&&(!isoperator(infix[i-1]))){
        printf("no operator before the ( \n");
        return 1 ;
       }
        if((infix[i]==')')&&(!isoperator(infix[i+1]))){
        printf("no operator after the ) \n");
        return 1 ;
       }

    }


  return 0 ;



}




// third menu

int sub_menu_2()

{
    int i ;

    do{


    printf("\t\t\t\t  *********");
    printf("\n\t\t\t  **************************");
    printf("\n\t***************************  MENU  ***************************\n\n\n");
    printf("\t\t1- Save\n");
    printf("\t\t2- evaluate\n");
    printf("\t\t3- Exit\n\n");
    printf("\nthe choice :");
    scanf("%d",&i);

    }while((i != 1)&&(i != 2)&&(i!=3));

    return (i);
}


//the second menu

int sub_menu()

{
    int i ;

    do{

    printf("\n\n\t\t\t\t  *********");
    printf("\n\t\t\t  **************************");
    printf("\n\t***************************  MENU  ***************************\n\n\n");
    printf("\t\t1- Convert to postfix\n");
    printf("\t\t2- Back\n");
    printf("\nthe choice :");
    scanf("%d",&i);

    }while((i != 1)&&(i != 2));

    return (i);
}


// finction to save the information in output file :equation,postfix expression,value

void save(FILE * out,char postfix[][80],char infix[][80])

{

    int i=0;

    for(i=0;i<strlen(postfix);i++)

     {
     fprintf(out,"the equation is :%s\n",infix[i]);
     fprintf(out,"the postfix is :%s\n",postfix[i]);
     }

}


// the driver function


void main()

{
    int len = 8;
    int i=0;
    FILE *in ;
    int j;
    in = fopen("data.txt","r");
    char infix[len][80];
    char postfix[len][80];
    int array[len];

    for (i=0;i<len;i++)
        array[i]=0;



for( ; ; )


{


  i=menu();

  switch(i)

  {
      case 1:read_data(in,infix);
      break;
      case 2:
                j = 0;
                for (j=0;j<strlen(infix[j]);j++)
                {

                    array[j] = compile(infix[j]);

                  if(array[j]==1)

                  printf("\nthere is error in line %d\n",j+1);

                  else

                  printf("there is no error in line %d\n",j+1);
                }

                  int sub=sub_menu();

            switch(sub)

                {
                case 1:
                        j=0;
                        int m = 0;
                        for(j=0;j<strlen(infix[j]);j++){
                           if (array[j]==0){
                            convert(infix[j],postfix[m]);
                            m++;
                           }
                        }


                        int s=sub_menu_2();

                        FILE *out;

                        out=fopen("out.txt","w");

                        switch(s)

                {
                        case 1:
                        {

                            save(out,postfix,infix);
                            fclose(out);

                        }break;

                        case 2:
                        {
                            FILE * output;
                            output=fopen("output.txt","w");
                            char in[100],post[100];
                           printf("Enter infix expression\n");

                            scanf("%s",in);
                            convert(in,post);

                            printf("the value :%d\n",evaluate(post));
                            fprintf(output,"infix expression :%s,postfix expression:%s,the value :%d",in,post,evaluate(post));
                            fclose(output);
                        }

                        break;
                        case 3:exit(0);
                            break;

                        }
                        break;

                        case 3:exit(0);
                        break;
                        }
                        break;


                        case 3: exit(0);
                        break;

  }
}


return (0);

}