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+//Solved Example 5:
+//Convering an infix expression to a Postfix Expression:
+function[sta]=push(stac,ele)
+  sta=0;
+  if(stac.top==0)
+    stac.a=ele;
+    stac.top=stac.top+1;
+  else
+    stac.a=[stac.a(:,:) ele]
+    stac.top=stac.top+1;
+  end
+  disp(stac);
+  sta=stac;
+endfunction
+
+function[ele,sta]=pop(stack)
+  ele='-1';
+  if(stack.top==0)
+    disp("Stack Underflow");
+    break;
+  else
+    ele=stack.a(stack.top);
+    stack.top=stack.top-1;
+    if(stack.top~=0)
+      b=stack.a(1);
+    for i2=2:stack.top
+      b=[b(:,:) stack.a(i2)];
+    end
+    stack.a=b;
+  else
+    stack.a='0';
+  end
+  end
+  sta=stack;
+endfunction
+function[l]=strlen(x)
+  i=1;
+  l=0;
+  [j,k]=size(x)
+  for  i=1:k
+    l=l+length(x(i));
+  end
+endfunction
+function[p]=pre(s1,s2)
+     i1=0;
+    select s1,
+    case '+' then i1=5;
+    case '-' then i1=5;
+    case '*' then  i1=9;
+    case '/' then i1=9;
+    end
+    i2=0;
+    select s2,
+    case '+' then i2=5;
+    case '-' then i2=5;
+    case '*' then  i2=9;
+    case '/' then i2=9;
+    end
+    p=0;
+    p=i1-i2;
+    if(s1=='(')
+      p=-1;
+    end
+    if(s2=='('&s1~=')')
+      p=-1;
+    end
+    if(s1~='('&s2==')')
+      p=1;
+    end
+    
+  endfunction
+function[a2]=intopo(a1,n)
+  stack=struct('a',0,'top',0);
+  l1=1;
+  l2=strlen(a1(1))
+  for i=2:n
+    l2=l2+strlen(a1(i))
+  end
+  a2=list();
+  while(l1<=l2)
+    symb=a1(l1); 
+    if(isalphanum(string(a1(l1))))
+      a2=list(a2,symb);
+    else
+      while(stack.top~=0&(pre(stack.a(stack.top),symb)>=0))
+        [topsymb,stack]=pop(stack);
+        if(topsymb==')'|topsymb=='(')
+          a2=a2;
+        else
+          a2=list(a2,topsymb);
+        end
+      end
+      if(stack.top==0|symb~=')')
+        stack=push(stack,symb);
+      else
+        [ele,stack]=pop(stack);
+      end
+    end
+    l1=l1+1;
+  end
+  while(stack.top~=0)
+    [topsymb,stack]=pop(stack);
+    if(topsymb==')'|topsymb=='(')
+      a2=a2;
+    else
+      a2=list(a2,topsymb);
+    end
+  end
+  disp(a2);
+endfunction
+//Calling Routine:
+a1=['(' '2' '+' '3' ')' '*' '(' '5' '-' '4' ')']
+a2=intopo(a1,11)
+\ No newline at end of file