CS 1400

1
CS 1400

• 1 Sept 2006

2
Your first C program

• Boilerplate
• // Cannon, demo program
• include ltiostreamgt
• using namespace std
• int main()
• // program goes here
• return 0

3
Output

• Pseudocode
• Print Enter a number
• C
• cout ltlt Enter a number
• Pseudocode
• Print square
• C
• cout ltlt square

4
Input

• Pseudocode
• Get value from user
• C
• cin gtgt value

5
Assignments

• Pseudocode
• Square n n
• C
• square n n
• Pseudocode
• Pay hours 40 (hours-40) Overtime_pay
• C
• pay hours 40 (hours-40) overtime_pay

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Declarations

• All variables must be established or declared
  prior to use usually at the top of the program
• Integers are declared using int. For example
• int value
• int width, height, depth
• A variable name must begin with a letter,
  followed by letters, digits, or underscores.

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Pseudocode Example

• Write a program to calculate the volume of a
  box, using dimensions provided by the user.
• Print Enter height, width, and depth of box
• Get height from user
• Get width from user
• Get depth from user
• volume height width depth
• Print Volume is
• Print volume

8
C boilerplate

• // Cannon, demo program
• include ltiostreamgt
• using namespace std
• int main()
• return 0

9
Adding C instructions

• // Cannon, demo program
• include ltiostreamgt
• using namespace std
• int main()
• int height, width, depth, volume
• cout ltlt Enter height, width, and depth
• cin gtgt height gtgt width gtgt depth
• volume height width depth
• cout ltlt Volume is ltlt volume
• return 0

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C is case sensitive!

• Use lower case for simplicity
• Upper case or underscore may be used to separate
  multi-word variable names
• int phone_number // easiest to read
• int phoneNumber // easier to read
• int phonenumber // not as easy to read

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Extended syntax

• Input and output statements can be cascaded
• cin gtgt height gtgt width gtgt depth
• cout ltlt the value of width is ltlt width
• Declarations can be a list
• int height, width, depth, volume
• Output messages can include control characters
  such as \n (new line) and \a (beep)
• cout ltlt This appears on line 1 \n This is on
  line 2
• Output messages may output endl to force a new
  line
• cout ltlt this is line1 ltlt endl ltlt This is line
  2

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Chapter 2 issues --

• Key words Table 2.4 (4th edition)
• Gloss over (for now)
• Section 2.3
• Section 2.7
• Section 2.9
• Section 2.10
• Section 2.16

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Integer variables

• Declaring variables as type int
• Only allows them to hold an integer ( or -)
• Range -2,147,483,648 to 2,147,483,647
• Variations
• unsigned int
• long
• short etcetera

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Floating point variables

• Declaring variables to be type float
• Allows them to hold an approximate floating-point
  value (precision to 6 digits)
• Range /- 3.4 x 10-38 to /- 3.4 x 1038
• Constants may be expressed in floating-point
  notation or E-notation
• E-notation is like scientific notation
• 3.14 x 105 is the same as 3.14E5