\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 6}
\date{August 7, 2009}
\begin{document}

\begin{frame}
\maketitle
\end{frame}

\begin{frame}
  \frametitle{Summary of previous lecture: Statement}
  \begin{itemize}
  \item Simple statemets are expressions followed by |;|
  \item Compound statements are a sequence of statements enclosed in a pair of braces.
  \item Conditionals; |if| and |if else| statements.
  \item Loops; while loop and for loop.
  \end{itemize}
\end{frame}

\begin{frame}
  \frametitle{Arrays}
  \begin{block}{Declaration}
  type variable[integer];
  type variable[]={values};
  \end{block}
  Eg,
  \begin{spec}
    int x[100];
    double mass[100];
    int u[] = {10,11,12,13,14}
  \end{spec}

\end{frame}

\begin{frame}
  \frametitle{Character type}
  \begin{spec}
    char foo = 'A';
    char foo = '\65';
    char foo = 65;
  \end{spec}
  
  \pause
  \begin{block}{Character escapes}
    \begin{itemize}
    \item |'\n'| is new line,
      \pause
    \item |'\t'| is tab,
      \pause
    \item |'\65'| is the character with ascii value 65,
      \pause
    \item |'\\'| is a back slash character.
    \end{itemize}
  \end{block}
  
\end{frame}
  
\begin{frame}
  \frametitle{Strings}
  \begin{itemize}
  \item Strings are character array.
  \item Strings are terminated with a null character |'\0'|.
  \end{itemize}
  \begin{spec}
    char mesg[] = { 'h','e','l','l','o','\0'}
    char mesg[] = "hello";
  \end{spec}
  
\end{frame}

\begin{frame}

  \frametitle{The |printf| and |scanf| function}

  \begin{spec}
    printf(fmtstring,e_1,e_2...e_n);
    scanf(fmtstring,&v1,&v2,...,&v_n);
  \end{spec}
  
  Eg.
  \begin{code}
    #include <stdio.h>
    int main()
    {
      double h,w;
      double area,per;
      printf("Enter the height and width: ");
      scanf("%g %g",h,w);
      area = h * w;
      per  = 2 * (h + w);
      printf("For a %g x %g rectangle\n\t",h,w);
      printf("Area = %g\n\tPerimeter = %g\n", area, per);
    }
  \end{code}
\end{frame}
\begin{frame}
  \frametitle{Format specifier for |printf| and |scanf|}

  \begin{itemize}
  \item All formating specifier is a |%| followed by a character,
  \item To print a literal |%| use |%%|,
  \item Depending on what follows |%| we have the following meanings
    \begin{tabular}{ll}
      |d|, |x|, |o| &  integer in decimal, hex or octal\\
      |f|           & float\\
      |g|           & generic floating point, i.e. float or double.\\
      |c|           & character
    \end{tabular}
  \end{itemize}
  For more formating characters check out manpage of scanf.
\end{frame}
\end{document}





\begin{frame}
  \frametitle{How to design loops?}
  
  \begin{definition}
    An invarient of a loop is a condition that is
    true always during the execution of the loop.
  \end{definition}
  
  Eg.
  
  \begin{spec}
    int sum = 0;
    int i   = 0;
    while( i < n)
    {
      i++;
      sum += i;
    }
  \end{spec}

  A nice invarient is $sum = \sum_{j=0}^i i$.
  
\end{frame}