\documentclass{beamer}
%include lhs2TeX.fmt
\author{Piyush P Kurur\\
  Office no: 224\\
  Dept. of Comp. Sci. and Engg.\\
  IIT Kanpur}

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\title{Fundamentals of Computing: Lecture 3}
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\usepackage{multicol}
\date{July 31, 2009}
\begin{document}
\begin{frame}
\maketitle
\end{frame}
\begin{frame}
  \frametitle{Getting started}

  
  You need to first creat a file using the editor.
  Use one of vi/emacs.

  The Lab TA will tell you how to use the editor.

  \begin{block}{Algorithm to creating a file and execute}
 
    \begin{enumerate}
    \item Open the file with the editor
      \begin{code}
        $ emacs foo.c
      \end{code}
    \item Edit the program save and exit. \label{step-edit}
    \item Compile the program
>
>       $ gcc foo.c
>        
     
    \item If there are errors go to step~\ref{step-edit}
    \item Run the program
>
>        $ ./a.out
>     
 
    \end{enumerate}
    \end{block} 
\end{frame}

\begin{frame}
  \frametitle{The first C program}
  
  \begin{code}
    #include<stdio.h>
    
    int main()
    {
      printf("The answer is 42")
    }
  \end{code}
\end{frame}


\begin{frame}
  \frametitle{Variables}
  \begin{code}
    #include <stdio.h>
    
    int main()
    {
      int answer = 41;
      printf("The answer is %d",answer);
      answer = answer  + 1;
      printf("The answer is %d",answer);
    }
  \end{code}

  \begin{block}{Rule for variable names}
  A variable name can start with any letter and contain
  any letter digit. The symbol |'_'| is treated as a letter.

  eg |x123|, |_x123|

  non examples |23x|
  \end{block}

\end{frame}

\begin{frame}
 \frametitle{Basic types}
  \begin{enumerate}
  \item Integers
>    int  i = 100;
   \item Character
>    char  c = 'a';
   \item Floting point numbers
>    float f = 1.234;
  \end{enumerate}     
\end{frame}

\begin{frame}
\frametitle{Expression}

\begin{itemize}
\item Usual aritmetic expressions.
 
 eg |x + y * 3|

\item Relational expressions 
 
>        x <= 15

\item Boolean (truth) expressions
> (x <= 10) || (y < 100) && (10 > 100)

Here the operator @||@ denotes a logical OR function and |&&| denote
logical AND function.

\end{itemize}

\begin{block}{Important point}

C does not have Boolean (or truth) type.  Integers, characters, etc
are treated like boolean. Zero is treated as False and non-zero as
True.

\end{block}
\end{frame}

\begin{frame}
\frametitle{Operator Precedence}
 What does  |2 + 3*6 > 5 && 5 < 2| mean ?
 \pause
 \begin{block}{Precedence rules among different kinds of operators}
   \begin{itemize}
   \item Arithmetic has highest
   \item then comes relational.
   \item then comes boolean.
   \end{itemize}
 \end{block}
 \begin{block}{Among arithmetic operators}
   \begin{itemize}
   \item @*@ and @/@ have more precedence than |+| and |-|.
   \item Unary operator has more precedence than binary.
   \end{itemize}
 \end{block}
\end{frame}

\begin{frame}
\frametitle{Factorial program}

\begin{code}
# include<stdio.h>

int main(){
   int n = 100;
   int i = 1;
   int fact = 1;
   while(i <= n)
   {
      fact = fact * i;
      i = i + 1;
   }
   printf("The factorial of %d is %d", n , fact);
}
\end{code}
    

\end{frame}
\end{document}