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

\usepackage{tikz}
\usepackage{multicol}

\usetikzlibrary{positioning,shapes,chains}
\usetikzlibrary{shapes.symbols}
\usetikzlibrary{matrix}
\usepackage{dot2texi}
\input{../include/grammar.tex}
\title{Fundamentals of Computing: Lecture 4}
\date{August 3, 2009}
\begin{document}
\begin{frame}
\maketitle
\end{frame}

\begin{frame}
  \frametitle{Summary of previous lecture (Variables)}
  \begin{itemize}
  \item Variables are memory location where values are stored
  \item They have a name, a type associated with them and a value.
  \item The name of a variable can start with a letter and contain
    letter or digit.
  \item The special character |_| (under score) is considered as a letter.
  \item The value associated can be changed using an assignment.
  \end{itemize}
  
\end{frame}

%\begin{frame}
%  \frametitle
%  \input{syntax/variable.tex}
%\end{frame}

\begin{frame}
  \frametitle{Summary Operator precedence}
  
  \begin{itemize}
    \item Arithmetic operators
      \uncover<2->{
        \begin{itemize}
        \item Unary operators (unary -)
        \item |*|, |/|
        \item |+|, |-|
        \end{itemize}
      }
    \item relational operators
    \item boolean operators
  \end{itemize}
  \uncover<3->{
    eg |- 4 * 3 < 1 && 2 > x + 5 | is same as
    |((-4) * 3) < 1) && (2 > (x + 5))|
  }
  
\end{frame}

\begin{frame}
  \frametitle{Integer expressions}
  \begin{itemize}
  \item Variable declaration
    \begin{spec}
      int x;
      int foo=100;
    \end{spec}
  \item Printing
    \begin{spec}
      printf("The value of integer variable %d\n",x);
    \end{spec}
  \item Arithmetic operators
    |+|,|-|,|*|,|/|, |%|, |-| (unary minus) etc
  \item Relational operators.
    |<|,|<=|,|>|, |>=|, |==| etc
  \end{itemize}
  \begin{block}{Important}
    The operator for checking for equality is |==| and not |=|.
  \end{block}
\end{frame}

\begin{frame}
  \frametitle{Factorial program}  
  \begin{code}
    # include<stdio.h>
    
    int main(){
      unsigned int n;
      int i = 1;
      printf("Enter the value: ");
      scanf("%d",&n);
      unsigned int fact = 1;
      while(i <= n)
      {
        fact = fact * i;
        i = i + 1;
      }
      printf("The factorial of %u is %u\n", n, fact);
    }
  \end{code}

\end{frame}

\begin{frame}
  \frametitle{Why did the factorial program go wrong?}
  \pause
  \begin{block}{Answer}
    Integers are of fixed precision typically 32 bits.
  \end{block}
\end{frame}

\begin{frame}
  \frametitle{Real numbers expressions}
  \begin{itemize}
  \item Variable declaration
    \begin{spec}
      float x;
      float pi=3.141;
      double avagadro = 6.023e23;
    \end{spec}
  \item Printing
    \begin{spec}
      printf("Values are %f, %g\n",x,avagadro);
    \end{spec}
  \item Arithmetic operators and relational operators are similar to integers.
  \end{itemize}
  \begin{block}{Important}
    Use double always. That gives better precission.
  \end{block}
\end{frame}


\begin{frame}
  \frametitle{Integers and Floats}
  C does automatic coversion between integers and floats.
  \begin{itemize}
  \item Integer to  Float/Double extension
  \item Float/Double to integer truncation
  \end{itemize}
  
  Unfortunately this is a very bad design.
  
  \begin{spec}
    int u = 10;
    int v = 11;
    float av;
    av = (u + v)/2 
    prinf("%f",av);
  \end{spec}

\end{frame}

\begin{frame}
  \frametitle{Assignments}
  
  Assignment is used to modify the value of a variable.
  
  eg.
  \begin{spec}
    x = 10;
    foo = 4.2;
  \end{spec}

  \pause
  \begin{block}{Assignment as expression}
    In C assignment itself is an expression.
    \begin{spec}
      x = y = 10; 
    \end{spec}
  \end{block}
  \pause
  \begin{block}{Special assignment}
  \begin{multicols}{2}
    \begin{spec}
      i++;
      foo *= 10;
    \end{spec}
    \newpage
    \begin{spec}
      i = i + 1;
      foo = foo * 10;
    \end{spec}
  \end{multicols}
  \end{block}

\end{frame}

\begin{frame}
  \frametitle{Boolean}
  There are no booleans in C.
  
  Integers, characters etc all play the role of boolean

  value of 0 is false.
  value of nonzero is true.

  \pause
  \begin{block}{WARNING}
    
    \begin{spec}
      x = 100;
      if (x = 0)
      {
        printf("Null value unexpected");
      }else{
        printf("Good value");
      }
    \end{spec}
      
  \end{block}
\end{frame}
\end{document}