Update convert.c

added comments for better readability
This commit is contained in:
ashish4321 2017-09-19 10:44:51 +05:30 committed by GitHub
parent 6974f28d61
commit f361d45483

View File

@ -1,18 +1,22 @@
#include<stdio.h>
char stack[20];
int top = -1;
void push(char x)
//convert infix to postfix
#include <stdio.h>
char stack[20]; //declaring an empty stack
int top = -1; //declaring top of stack
void push(char x) //push function
{
stack[++top] = x;
stack[++top] = x; //each time it is pushed top is increamented
}
char pop()
char pop() //pop function
{
if(top == -1)
return -1;
else
return stack[top--];
return stack[top--]; //each time it is popped top is decreamented
}
int priority(char x)
int priority(char x) // to check the priority of characters
{
if(x == '(')
return 0;
@ -35,23 +39,24 @@ int main()
{
if(isalnum(*e))
printf("%c",*e);
else if(*e == '(')
else if(*e == '(') //push it directly into the stack
push(*e);
else if(*e == ')')
else if(*e == ')') //pop until we gwt the left parenthesis
{
while((x = pop()) != '(')
printf("%c", x);
}
else
{
while(priority(stack[top]) >= priority(*e))
while(priority(stack[top]) >= priority(*e)) //pop until priority of top of stack is greater than equal to priority of expressions character
printf("%c",pop());
push(*e);
push(*e); //otherwise push
}
e++;
}
// keep popping until top is not -1
while(top != -1)
{
printf("%c",pop());
printf("%c",pop());
}
}