CS 151

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CS 151

• Lecture 3
• Programming in C

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ACM Tour on Saturday

• The Local ACM Chapter is having a tour of
  computing facilities on campus on Saturday at
  3PM.
• See Announcements for Details.
• Good opportunity to meet upperclassfolk,
• women CS students are particularly encouraged to
  come and meet

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Programming in C

• A C program consists of functions.
• Functions are starting points of execution.
• Every C program starts with a function called
  main
• Functions can accept input values, perform tasks,
  and possibly return computed values.

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Function Structure
int main (void) / C instructions here
/ return 0
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A Simple Program Printing

• Make a program that prints text on the screen.
• Basic outline of a C program
• Use a library function, printf()

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C Function Libraries

• C comes with a many libraries of "ready-made"
  functions.
• Two steps to using them.
• Use a include statement
• Call (invoke) the function, i.e. write it's name
  in your program.

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The printf() function

• Include the standard i/o (input/output) library
• include ltstdio.hgt
• Invoke the function.
• printf("Go Beavers")
• Text inside double quotes is called a string.
• printf() prints strings on the output screen.

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A simple program printing
/ Name Collaborator(s) Instructor
Date Assignment Description
/ include ltstdio.hgt / preprocessor
directive / int main (void) printf("Go
Beavers") / print some text / return 0
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• Header block
• /
• Name
• Collaborator(s)
• Instructor
• Date
• Assignment
• Description
• /
• C compiler ignores it.
• Required in this course.

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Preprocessor include ltstdio.hgt Include the
library file named stdio.h as part of this
program. . Comments / print some text / This
is a programmers comment an explanation of
the meaning of this part of the program. It is
ignored by the compiler.
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Main Function
int main (void) printf("Go Beavers")
return 0 All programs in the C language
start with the function main. A function is a
named unit of computation in the C language. For
this class, the last statement in main is always
return 0 Execution is line by line starting
after the opening brace, , and ends with the
closing brace, .
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Console (Screen) I/O
I/O means Input/Output printf("Go
Beavers") printf means print formatted to the
screen using certain formatting rules.
Characters inside double quotes are called a
string constant or string literal.
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Formatting Characters in Strings

• '\n' called the newline character. Causes
  screen cursor to move down one line and to left.
• '\t' called the tab character. Causes cursor to
  move to next tab stop on screen.
• ' ' called the space character. Shows up as
  blank space on screen.

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Using Formatting characters

• printf("one\ntwo") prints
• one
• two
• printf("one\ttwo") prints
• one two
• printf("one two three") prints
• one two three

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Print Specifiers and Parameters

• printf() can have more than one parameter.
• printf("s\ns", "one", "two")
• which prints
• one
• two

parameter two
parameter three
parameter one
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The Big Picture

• The source of a C-Program is a text file called
  source code.
• The compiler reads the source and reports errors.
• Execution starts at beginning of main()
  function.
• The program executes line by line.

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Some Details

• C is case sensitive
• (printf not same as Printf).
• White Space in the source code (program) is
  ignored by the compiler.
• Spaces, tabs, newline (Enter key).
• Things have names.
• include, main, printf, return.
• CodeWarrior color codes reserved words
• Punctuation, other symbols have specific meaning.
• , ltgt \ ...

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Using Code Warrior
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Create Folder for Programs

• Create a folder on your z drive (e.g. cs151).
• Always create a new project starting in this
  folder.
• CodeWarrior will create a new folder under this
  folder for each new program using your project
  name as the folder name (e.g. pgm1)

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Starting Code Warrior
Start the CodeWarrior Integrated Development
Environment
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Start a new project (program)
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The New Project Dialog
click
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The File Dialog
3rd
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Project Type
2nd
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Select Project Stationery
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Project Window (locked)
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Make It An MDI Child
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The Project Window
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The Edit Window
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Click the RUN Button
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The Output Window
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Questions?

• Read Chapter 2
• Get started on Programming Assignment 1
• Take Quiz 1 on BlackBoard starting Monday