From 49d82f1fdeb7825fcc77766f8afbbd4a2589d071 Mon Sep 17 00:00:00 2001
From: Christian Bender <christianbender89@web.de>
Date: Thu, 14 Feb 2019 15:51:36 +0100
Subject: [PATCH] refactoring

---
 data_structures/stack/main.c | 139 ++++++++++++++++++-----------------
 1 file changed, 70 insertions(+), 69 deletions(-)

diff --git a/data_structures/stack/main.c b/data_structures/stack/main.c
index 8436a30e..6a1502bb 100644
--- a/data_structures/stack/main.c
+++ b/data_structures/stack/main.c
@@ -1,82 +1,31 @@
-//program for stack using array 
+//program for stack using array
+
+#include <stdio.h>
 
-#include<stdio.h>
 void push();
 void pop();
-void peep();
+void peek();
 void update();
+
+int a[100], top = -1;
+
 int main()
 {
-    int n,a[100],top=0;
-    //function for pushing the element 
-    void push()
-    {
-        printf("\nenter the value to insert");
-        scanf("%d",&n);
-        top=top+1;
-        a[top]=n;
-    }
-    //function for poping the element out
-    void pop()
-    {
-        if(top==0)
-        {
-            printf("\nstack is empty");
-        }
-        else
-        {
-            int item;
-            item=a[top];
-            top=top-1;
-            printf("\npoped item is %d ",item);
-        }
-    }
-    //function for peeping the element from top of the stack
-    void peep()
-    {
-        int i;
-        printf("\nenter the element position to view from top");
-        scanf("%d",&i);
-        if(top-i+1<0)
-        {
-            printf("\nunderflow condition");
-        }
-        else
-        {
-            int x;
-            x=a[top-i+1];
-            printf("\nthe %dth element from top is %d",i,x);
-        }
-    }
-    //function to update the element of stack
-    
-    void update()
-    {
-        int i,n;
-        printf("\nenter the position to update");
-        scanf("%d",&i);
-        printf("\nenter the item to insert");
-        scanf("%d",&n);
-        if(top-i+1<0)
-        {
-            printf("\nunderflow condition");
-        }
-        else
-        {
-            a[top-i+1]=n;
-        }
-    }
+
     int x;
-    while(1)
+    while (1)
     {
+        printf("\n0.exit");
         printf("\n1.push");
         printf("\n2.pop");
-        printf("\n3.peep");
+        printf("\n3.peek");
         printf("\n4.update");
-        printf("\nenter your choice");
-        scanf("%d",&x);
-        switch(x)
+        printf("\nenter your choice? ");
+        scanf("%d", &x);
+        switch (x)
         {
+        case 0:
+            return 0;
         case 1:
             push();
             break;
@@ -84,7 +33,7 @@ int main()
             pop();
             break;
         case 3:
-            peep();
+            peek();
             break;
         case 4:
             update();
@@ -93,6 +42,58 @@ int main()
             printf("\ninvalid choice");
         }
     }
-    return(0);
+    return (0);
 }
 
+//function for pushing the element
+void push()
+{
+    int n = 0;
+    printf("\nenter the value to insert? ");
+    scanf("%d", &n);
+    top += 1;
+    a[top] = n;
+}
+
+//function for poping the element out
+void pop()
+{
+    if (top == -1)
+    {
+        printf("\nstack is empty");
+    }
+    else
+    {
+        int item;
+        item = a[top];
+        top -= 1;
+        printf("\npoped item is %d ", item);
+    }
+}
+
+//function for peeping the element from top of the stack
+void peek()
+{
+    if (top >= 0)
+        printf("\n the top element is %d", a[top]);
+    else
+        printf("\nstack is empty");
+}
+
+//function to update the element of stack
+void update()
+{
+    int i, n;
+    printf("\nenter the position to update? ");
+    scanf("%d", &i);
+    printf("\nenter the item to insert? ");
+    scanf("%d", &n);
+    if (top - i + 1 < 0)
+    {
+        printf("\nunderflow condition");
+    }
+    else
+    {
+        a[top - i + 1] = n;
+    }
+}
\ No newline at end of file