maininfixtopostfixandevalution.c

#include<stdio.h>
#include<stdlib.h>
#define N 20
#define M 80

char val;

int isoprator(char ch)
{
    if(ch=='^'||ch=='*'||ch=='/'||ch=='+'||ch=='-')
        return(1);
    else
        return(0);
}

int isoprand(char ch)
{
    if((ch>='0'&&ch<='9'
        )||(ch>='a'&&ch<='z')||(ch>='A'&&ch<='Z'))
        return(1);
    else
        return(0);
}

int prac(char ch)
{
    if(ch=='^')
        return(3);
    else if(ch=='*'||ch=='/')
        return(2);
    else if(ch=='+'||ch=='-')
        return(1);
    else
        return(0);
}

void push(char s[],int *top,char val)
{
        if(*top<(N-1))
        {
            (*top)++;
            s[*top]=val;
        }
        else
            printf("stack is full\n");
}
char pop(char s[],int *top)
{
        if((*top)>-1)
        {
            val=s[*top];
            (*top)--;
            return val;
        }
        else
            printf("stack is empty\n");
        return(-1);
}

int read(char s[],int top,int i)
{
    if((top-i+1)>=0)
        return s[top-i+1];
    else
        printf("not found\n");

}

int isempty(char s[],int top)
{
    if(top==-1)
        return(1);
    else
        return(0);
}

void infixtopostfix(char *i,char *p)
{
    char s[N];int top=-1;
    while(*i!='\0')
    {
        if(isoprand(*i))
        {
            *p=*i;
            *i++;
            *p++;
        }

        else if (*i=='(')
        {
           push(s,&top,'(');
           *i++;
        }
        else if(*i==')')
        {
            while(read(s,top,1)!='(')
            {
                *p=pop(s,&top);
                *p++;
            }
            *i++;
	    pop(s,&top);
        }
        else if(isempty(s,top)||read(s,top,1)=='('||prac(*i)>prac(read(s,top,1)))
        {
            push(s,&top,*i);
            *i++;
        }



        else
        {
            *p=pop(s,&top);
            *p++;
        }
    }
    while(!isempty(s,top))
    {
        *p=pop(s,&top);
        *p++;
    }
}

int evaluate(char *p)
{
    char s[N];
    int top=-1;
    int a=0,b=0,val=0,num,ans=0;
    push(s,&top,'(');
    while(*p!='\0')
    {
        if(isoprator(*p))
        {
            b=pop(s,&top);
            a=pop(s,&top);
            switch(*p)
            {
                case '+':
                val=a+b;
                push(s,&top,val);
                *p++;
                break;

                case '-':
                val=a-b;
                push(s,&top,val);
                *p++;
                break;

                case '*':
                val=a*b;
                push(s,&top,val);
                *p++;
                break;

                case '/':
                val=a/b;
                push(s,&top,val);
                *p++;
                break;

                case '^':
                val=a^b;
                push(s,&top,val);
                *p++;
                break;
            }

        }
        else
        {
            num=*p-'0';
            push(s,&top,num);
            *p++;
        }
    }
    ans=pop(s,&top);
    return ans;
}

void main()
{   int ans;
    char infix[M]={};
    char postfix[M]={};
    printf("Infix Expression = ");
    scanf("%s",infix);
    infixtopostfix(infix,postfix);
    printf("Postfix Expression = %s",postfix);
    ans=evaluate(postfix);
    printf("\nAnswer of Postfix Evalution = %d",ans);
}

/* ""OUTPUT""

Infix Expression = 8+9*7
Postfix Expression = 897*+
Answer of Postfix Evalution = 71

*/