C Programming Basics Chapter 1 Lecture CSIS 10A

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C Programming BasicsChapter 1 LectureCSIS 10A
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Agenda

• Hardware Basics ?
• The IDE
• My First Program
• Its all G(r)eek to me
• Variables and Declarations
• Input and Output

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Anatomy of a Computer
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The CPU uses machine language

• Assembly instructions to calculate the radius of
  a circle
• LOAD radius
• LOAD pi
• MULTIPLY
• LOAD two
• MULTIPLY
• STORE circle

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Compilers to the Rescue !

• High level languages like C allows writing code
  that is easier to understand and universally
  works on any CPU.
• circle2.0radiuspi
• The compiler is what translates instructions
  from C into Machine language.

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Agenda

• Hardware Basics
• The IDE ?
• My First Program
• Its all G(r)eek to me
• Variables and Declarations
• Input and Output

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THE MECHANICS OF WRITING A PROGRAM

• Editing -- Writing a program
• Compiling -- Translating from C into machine
  language
• Linking -- Combining your program with other
  libraries
• Running Letting the computer execute a program
• Debugging Running step by step through a
  program searching for mistakes
• The Integrated Development Environment (IDE)
  combines 1-5.

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Agenda

• Hardware Basics
• The IDE
• My First Program ?
• Its all G(r)eek to me
• Variables and Declarations
• Input and Output

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Hello World !

• Lets start off the traditional way
• Program that prints out Hello World on your
  output console (your screen)
• Lets start off on our journey..

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Steps

• Create new source file
• Write the code
• Create a workspace (only in MSVC)
• Compile
• Link
• Execute

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Agenda

• Hardware Basics
• The IDE
• My First Program
• Its all G(r)eek to me ?
• Variables and Declarations
• Input and Output

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Its all G(r)eek to me

• actually, its C
• Lets dissect and analyze a simple program

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20,000 ft. above sea level

• include ltiostreamgt
• using namespace std
• int main()
• // This is my first program
• cout ltlt "Hello World" ltlt endl
• system("pause")
• return 0

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20,000 leagues under the sea

• include ltiostreamgt
• Actually includes some information into your code
• Contains some definitions that are needed for
  your code
• More of this later on in the course

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22,000 leagues under the sea

• using namespace std
• This line refers to a set of standard object name
  definitions
• For now, this is boilerplatestick it in cause
  it makes everything work!!

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deeper.

• int main()
• This is the piece of code (function) that is
  operated on first when a program is executed
• Whats a function ???
• . all thats coming soon

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even deeper.

• //This is my first program
• This is a comment you write to yourself
• Useful when writing large programs
• Starts with a //

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and deeper..

• Output operator
• cout ltlt Hiltltendl
• cout is the console monitor (your display)
• ltlt is the output operator. Use to chain together
  your output message.
• Hiis a string literal
• endl means end-line (like enter key)

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getting sleepy?..

• For the Bloodshed environmentHold the display
  open so you can read it (pressing a key will
  continue) system("pause")
• Finish up this program, return a 0 to operating
  system (everything ended OK)
• return 0

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and even deeper .

• delineates the code block
• Each line ends with a

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Other types of cout statement

• coutltlt my age is ltltendl ltlt 39ltltendl
• coutltlt my age is 39
• coutltlt whats yours
• Escape with \
• Output a coutltlt \ ltltendl
• Output a endl coutltlt\n

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Toms All Purpose Program Shell

• include ltiostreamgt
• using namespace std
• int main()
• // Your code here ...
• system("pause")
• return 0
• Future slides may neglect some of the above
  components for clarity

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You Do It

• Modify your hello world program to print your
  name, address and phone number (COULD BE FAKE!)
  on three lines
• Tom Rebold
• 1600 Pennsylvania Ave
• 123-456-7890
• Experiment with line breaks

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Lets get moving..

• Well learn as we proceed
• Youll be saying Aha! or Oho! when you hear
  these terms again
• Lets play around a bit more

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What more ?

• Variables and Declarations
• Getting User Input

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Variables and Declarations

• Variables represent storage locations in the
  computers memory
• variable expression
• Assignment is from right to left
• n 5
• Would give n the value 5

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Using int Variables

• int main()
• int m,n
• m 44
• cout ltlt m ltlt m
• n m 33
• cout ltlt and n ltlt n ltlt endl

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Clearing the haze

• int m

m 44.0
44
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Clearing the haze

• int m 44, n

n m 33
44 33 77
77
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Want more ?

• Variables and Declarations
• Getting User Input

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User Input with cin

• How shall I feed in data ?
• Remember cout ?
• Meet cin
• cin gtgt m
• Will put the value entered through the console
  (keyboard) into m

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User Input with cin

• int main()
• cout ltlt "Enter the value of m"
• cin gtgt m
• cout ltlt "m " ltlt m ltlt endl

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User Input with cin

• int main()
• cout ltlt Enter the value of m
• cin gtgt m
• cout ltlt m ltlt m ltlt endl

HEY THERES SOMETHING WRONG HERE !!!
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User Input with cin

• int main()
• int m
• cout ltlt "Enter the value of m"
• cin gtgt m
• cout ltlt "m " ltlt m ltlt endl

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Your turn ()

• from hello.cpp FilegtSaveAs age.cpp
• Delete all the cout statements. Add lines to
• a) Declare a variable called age
• b) Display a message asking for data (such as
  tell me your age)c) read the data into age
  d) display the variable age with a descriptive
  message. (refer to slide 34)

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Thats a wrap !

• What we learned so far
• How to write a basic C program
• The structure of a program
• Displaying to the console (cout)
• Variables
• Getting user input via the console (cin)