1. Lecture2

2. Lecture Outline The Software Development Method Exercise
C Language Elements
Preprocessor Directives
Function Main
Declarations
Executable Statements
Reserved Words, Standard Identifiers & User-Defined Identifier
User-Defined Identifier Rules
Reading: Chapter 2

3. The Software Development Method
1. Specify the problem requirements.
2. Analyze the problem.
3. Design the algorithm to solve the problem.
4. Implement the algorithm.
5. Test and verify the completed program.
6. Maintain and update the program.
C Language Elements

4. Exercise
Write a program to process a collection of daily temperatures. Your program should count and print the number of hot days (85 or higher), the number of pleasant days ( ), the number of cold days (less than 60). It should also display the category of each temperature.
C Language Elements

5. Exercise 1. Specify the problem requirements
A program is required to process daily temperatures and provide
the total number of hot, pleasant, and cold days.
2. Analyze the problem
Input:
Output:
temperature
total number of days in each category
3. Design the algorithm to solve the problem
1. Get the temperature.
2. Determine category of that temperature and increment counter
for that particular category.
3. Display categories and total number of days that fell under the
category.
C Language Elements

6. Flowcharts (Continue)
Start or End
Input or Output
Process or Calculation
Decision
Course Introduction

7. Exercise Yes >=85? No Yes <=60? No Start Get Temp Add 1 to Hot
Print Hot, Cold,
and Pleasant
<=60? No
Add 1 to Cold
Yes
Add 1 to Pleasant No
End
C Language Elements

8. C Language Elements Preprocessor Directive
A C program line beginning with # that provides an instruction to
the preprocessor.
Preprocessor
A system program that modifies a C program prior to its
compilation.
Two important preprocessor directives are:
#include
#define
C Language Elements

9. #include Preprocessor Directive
Syntax
#include <library>
Examples
#include <stdio.h>
#include <math.h>
C Language Elements

10. #define Preprocessor Directive
Syntax
#define NAME value
Examples
#define PI 3.14
#define section7 18
C Language Elements

11. C Language Elements Function Main
It marks the beginning of any C program.
Function Main
Syntax
int main(void) { }
(declarations)
(Executable statements)
C Language Elements

12. C Language Elements Declarations
The part of a program that tells the compiler the names of memory
cells in a program
Declarations
Executable Statements
Program commands that are converted to machine code by the
compiler.
C Language Elements

13. Declarations Syntax Data type variable; Examples int count, large;
float area;
char first;
int count,
large;
C Language Elements

14. Data Types It is a set of values.
It defines operations that can be performed on those values.
The most used data types are:
int
float
char
C Language Elements

15. int The int data type represents integers in C.
Integers are whole numbers.
ANSI defined the range of integers as being between and
32767
Examples:
-5235
13253
-35
32767
C Language Elements

16. Float The float data type represents real numbers in C.
A real number has an integral part and a fractional part separated by
a decimal point.
Examples:
3.643
0.325
3.4
C Language Elements

17. char The char represents one individual character in C. Examples: 'D'
'5'
'*'
C Language Elements

18. Reserved Words, Standard Identifiers & User-Defined Identifier
A reserved word is a word that has a special meanning in C and
cannot be used for other purpses.
Example: int, double, char, void.
A standard identifier is a word that has a special menning in C but
can be used for other purposes or redefined.
Example: printf, scanf.
A user-defined identifier is a name gevin to a variable.
Does not have a special meanning in C and needs to be declared.
Example: PI, large, hot.
C Language Elements

19. User-Defined Identifier Rules
An identifier must consist only of letters, digits, and underscores.
An Identifier cannot begin with a digit.
A C reserved word cannot be used as an identifier.
A standard identifier should not de redefined.
C Language Elements

20. User-Defined Identifier Rules
Examples:
letter2
21etter
Begins with a digit
letter_2
int
Reserved word
joe's
Character ’ not allowed
variable
cent_per_inch
C Language Elements

21. C Language Elements #include <stdio.h>
#define KMS_PER_MILE 1.609
int main(void) {
float miles, kms; }
(Executable statements)
C Language Elements