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//THIS PROGRAM IS TO COVERT THE INFIX TO POSTFIX EXPRESSION//STACK IS USED AND IT IS IMPLEMENTATION USING ARRAYS//CODEDAND COMPILED IN TURBO C#include#include#include//Defining the maximum size of the stac#define MAXSIZE 100//Declaring the stack array and top variables in a structurestruct stack{

char stack[MAXSIZE];int Top;

};//type definition allows the user to define an identifier that would//represent an existing data type. The user-defined data type identifier//can later be used to declare variables.typedef struct stack NODE;//this function will add/insert and element to Top of the stackvoid push(NODE *pu, char item){

//if the top pointer already reached the maximum allowed size then//we can say that the stack is full or overflowif (pu->Top == MAXSIZE - 1)

{ printf("\nThe Stack Is Full");getch();

}//Otherwise an element can be added or inserted by//incrementing the stack pointer Top as followselse

pu->stack[++pu->Top] = item;}//This function will delete an element from the Top of the stackchar pop(NODE *po){

char item = '#';

//If the Top pointer points to NULL, then the stack is empty//That is NO element is there to delete or popif (po->Top == -1)

printf("\nThe Stack Is Empty. Invalid Infix Expression");//Otherwise the top most element in the stack is poped or//deleted by decrementing the Top pointerelse

item = po->stack[po->Top--];return(item);

}//This function returns the precedence of the operatorint prec(char symbol){

switch (symbol){case'(':

return(1);case')':

return(2);case'+':

return(3);case'*':case'/':

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case'%':return(4);

case'^':return(5);

default:return(0);

}}//This function will return the postfix expression of an infixvoid Infix_Postfix(char infix[]){

int len, priority;int i, j;char postfix[MAXSIZE], ch;//Declaring an pointer variable to the structureNODE ps;//Initializing the Top pointer to NULLps.Top = -1;

//Finding length of the stringlen = strlen(infix);

//At the end of the string inputting a parenthesis ')'infix[len++] = ')';push(&ps, '(');//Parenthesis is ushed to the stackfor (i = 0, j = 0; i < len; i++)

{ switch (prec(infix[i])){

//Scanned char is '(' push to the stackcase 1:

push(&ps, infix[i]);break;//Scanned char is ')' pop the operator(s) and add to//the postfix expression

case 2:ch = pop(&ps);while (ch != '('){

postfix[j++] = ch;ch = pop(&ps);}break;//Scanned operator is +, - then pop the higher or same//precedence operator to add postfix before pushing//the scanned operator to the stack

case 3:ch = pop(&ps);while (prec(ch) >= 3){

postfix[j++] = ch;ch = pop(&ps);

}push(&ps, ch);push(&ps, infix[i]);break;//Scanned operator is *,/,% then pop the higher or//same precedence operator to add postfix before//pushing the scanned operator to the stack

case 4:ch = pop(&ps);while (prec(ch) >= 4)

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{postfix[j++] = ch;ch = pop(&ps);

}push(&ps, ch);push(&ps, infix[i]);break;//Scanned operator is ^ then pop the same//precedence operator to add to postfix before pushing//the scanned operator to the stack

case 5:ch = pop(&ps);while (prec(ch) == 5){

postfix[j++] = ch;ch = pop(&ps);

}push(&ps, ch);push(&ps, infix[i]);break;//Scanned char is a operand simply add to the postfix//expression

default:postfix[j++] = infix[i];

break;}}//Printing the postfix notation to the screenprintf("\nThe Postfix expression is = ");for (i = 0; i < j; i++)

printf("%c", postfix[i]);}int main(){

char choice, infix[MAXSIZE];do{

//clrscr();// system("cls");printf("\n\nEnter the infix expression = ");fflush(stdin);gets(infix);//Inputting the infix notationInfix_Postfix(infix);//Calling the infix to postfix functionprintf("\n\nDo you want to continue (Y/y) =");fflush(stdin);scanf("%c", &choice);

}while (choice == 'Y' || choice == 'y');}