Update convert.c

added comments for better readability

convert.c

@@ -1,18 +1,22 @@
-#include<stdio.h>
+//convert infix to postfix
-char stack[20];
+#include <stdio.h>
-int top = -1;
+char stack[20]; //declaring an empty stack
-void push(char x)
+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;
@@ -35,21 +39,22 @@ 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());