CSE399 C

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CSE399 - C

• January 8th, 2007
• Policies/Hello World

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Course Info

• Lecturer Drew Hilton (adhilton_at_cis)
• TA TBA
• Lectures M or W, noon Town 309
• Office hours TBA
• Webpage
• www.seas.upenn.edu/adhilton/cse399

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Overview

• C/C
• Somewhat flexible on topics
• Assuming you are eager to learn this

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Textbook

• No required textbook
• Google
• man pages
• Last years book
• C for Java Programmers
• By Mark A. Weiss

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Grading

• Homeworks 40
• Project 40
• Class attendance/participation 20
• I reserve the right to include in-class quizzes
  under this category if I feel it is needed

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Homeworks

• 1-2 weeks each
• Equally weighted
• Partner optional
• Due at start of class
• 5 grace days, then 20 pts/day
• Grading will be done on eniac-l

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Project

• Large program
• 1-3 people (pairs encouraged)
• Due at end of semester
• Propose topic before Spring Break

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Cheating Policy

• If I were watching, would you do it?
• Working in pairs OK
• Both partners must participate/learn
• Pair programming
• Separate code, debugging help etc
• Document who/how in comments
• Only your partner should see your code
• When in doubt ask me

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Now some C.

• include
• include
• int main (void)
• printf(Hello World\n)
• return EXIT_SUCCESS

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C compilation
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Whats in a header?

• Preprocessor definition
• define EXIT_SUCCESS 0
• Function prototypes
• Declare the argument/return types
• Example
• int factorial(int x)
• Note ends in semi-colon.
• External variable declarations (later)
• Type declarations (also later)

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A first approximation

• / maybe this is the prototype from stdio/
• void printf(string x)
• int main (void)
• printf(Hello World\n)
• return 0 / Replace defined symbol /

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Close, but

• C doesnt have a string type
• char represents a sequence of characters
• printf actually
• Returns int (number of characters printed)
• Takes a variable number of arguments
• int printf(char format, )

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A variable number of arguments?

• First arg format specifier string
• Contains directives (d, s, )
• Later args values to replace directives
• Example
• int x 3
• char s some string
• printf(x is d and s is s \n, x, s)

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Basically right

• int printf(char format, )
• int main (void)
• printf(Hello World\n)
• return 0
• (Actually, lots of other stuff defined in those
  headers)

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So whats like Java?

• Most basic syntax
• int i
• int counter 0
• for ( i 0 i
• if (xi
• counter
• return counter

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Caveat

• What about
• for (int i 0 i
• Error for loop initital declaration used
  outside C99 mode
• Solution compile with -stdc99

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Arrays somewhat similar

• Indexed the same xi
• Not objects dont have length field
• Just contiguos regions of memory
• Accesses not bounds checked
• Dynamic allocation is different
• (more on this later)

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Homework 1

• On webpage now
• Due Wed Jan 17th at noon by email
• Probably
• Get acquainted with Javalike parts of C
  discussed today
• Questions? email me.

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Questions?