/*
INTOPOST.C

Rex Jaechke, "C Users Journal" mach 92.
*/

#include <ctype.h>

void push(int);
int pop(void);

/*--------------------------------------------------------------------------

FUNCTION: intopost - converts infix to postfix

A. Push a ( on the stack. This sentinel allows us to detect when we
have flushed out the stack on completion in step 1.

--- Perform steps B through H for each character in the infix string ---

B. Ignore white space.

C. Pass alphabetic characters through to postfix list.

D. Push any ( on the stack. These sentinels allows us to detect when
have flushed out the stack when handling ) and operators.

E. Have a ) so pop off the stack and put into postfix list until a (
is popped. Discard the (.

F Have a * or /. Pop off any operators of equal or higher precedence
and put them into postfix list. If a ( or lower precedence operator
(such as + or -) is popped, put it back and stop looking.
Push new * or /.

G. Have a + or -. Pop off any operators of equal or higher precedence
(that includes all of them) and put them into postfix list. If a (
is popped, put it back and stop looking. Push new + or -.

H. Report unknown character on input.

--------

I. Have processed all input characters. New flush stack until we find
the matchint ( put there in step A.

J. Terminate the postfix list.

--------------------------------------------------------------------------*/

void intopost(const char *infix, char *postfix)
{
int st;

/*A*/ push('(');
while (*infix != '\0') {

#ifdef TRACE
printf("*infix: %c\n", *infix);
#endif

/*B*/ if (isspace(*infix)) {
;
}
/*C*/ else if (isalpha(*infix)) {
*postfix++ = *infix;
}
/*D*/ else if (*infix == '(') {
push('(');
}
/*E*/ else if (*infix == ')') {
while ((st = pop()) != '(')
*postfix++ = st;
}
/*F*/ else if (*infix == '*' || *infix == '/') {
while (1) {
if ((st = pop()) == '(' || st == '+'
|| st == '-') {
push(st);
break;
}
*postfix++ = st;
}
push(*infix);
}
/*G*/ else if (*infix == '+' || *infix == '-') {
while (1) {
if ((st = pop()) == '(') {
push(st);
break;
}
*postfix++ = st;
}
push(*infix);
}
/*H*/ else {
printf("Unknown input character %c\n", *infix);
}
++infix;
continue;
}
/*I*/ while ((st = pop()) != '(')
*postfix++ = st;

/*J*/ *postfix = '\0';
}



I Can Write In C Language But Cannot In Assembly SomeOne Can Try Please Do it

/* Fil Slut : INTOPOST.C */