An Introduction to C Programming

1
An Introduction to C Programming

• Geb Thomas

2
Learning Objectives

• Learn how to write and compile a C program
• Learn what C libraries are
• Understand the C variable types
• Understand how to use if and if/else statements
• Understand how to use the for structure

3
How to Write and Compile C Programs

• C, C and Java
• Compilers Microsoft Visual C, GCC, Borland C
• Since we will be working on PCs
• Microsoft Visual C
• Open new Win32 Console Application
• Name it (in project name)
• Click a hello world application
• Go to file view, source files, then the name of
  your project.cpp

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Some Things About C

• Case matters, white space does not
• Comments go between / and /
• Each statement is followed by a semicolon
• Execution begins in the main function
• int main(int argc, char argv) / ignore this
  /
• / start here /
• return 0 /end here /

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What are C libraries?

• C is a lightweight language. Most of its
  intelligence is compartmentalized in libraries.
• Almost all c programs use the stdio or standard
  input/output library. Many also use the math
  library.
• To use a library, include the header file (I.e.,
  stdio.h) at the top of the file.
• For most special purpose libraries (I.e., math)
  you need to include the library on the link line.
  In Visual C, go to project-gtsettings-gtobject/mo
  dule libraries.

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C Variable Types

• The most common types are char, int, float, and
  double.
• Strings are arrays of characters (well cover
  arrays later).
• Declare a variable before you use it
• int x / declares an integer called x. Its
  value is not assigned. /
• float y, z 3.14159 / declares two floating
  point numbers. z is set equal to pi /
• z 4 / now z is equal to 4 /
• myVal 2 / This would be an error, because
  myVal was not yet declared /

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Logical Operators

• C defines these logical operators lt, gt, lt, gt
  and (the equivalence operator)
• You can compare any variable. Characters are
  compared based on their ASCII values.
• All answers will be true (not zero) or false (0)
• You can extend the logic with (and), (not)
  and (or).

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The If Statement

• Syntax if (expression) statement
• If the expression is true (not zero), the
  statement is executed. If the expression is
  false, it is not executed.
• You can group multiple expressions together with
  braces
• if (expression)
• statement 1
• statement 2
• statement 3

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The If/Else Statement

• Syntax if (expression) statement_1 else
  statement_2
• If the expression is true, statement_1 will be
  executed, otherwise, statement_2 will be.
• if (myVal lt 3) printf(myVal is less than 3.\n)
• else printf(myVal is greater than or equal to
  3.\n)

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The For Loop

• Syntax for (initialization test increment)
  statements
• The for loop will first perform the
  initialization. Then, as long is test is TRUE,
  it will execute statements. After each
  execution, it will increment.
• for (cntr 0 cntr lt 3 cntr cntr 1)
• printf( Counter d\n, cntr)
• Counter 0
• Counter 1
• Counter 2

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Learning Objectives

• Learn how to write and compile a C program
• Learn what C libraries are
• Understand the C variable types
• Understand how to use if and if/else statements
• Understand how to use the for structure