C Programming Intro.ppt

1
Objectives
❏ To understand the structure of a C-language program.
❏ To write your first C program.
❏ To introduce the include preprocessor command.
❏ To be able to create good identifiers for objects in a program.
❏ To be able to list, describe, and use the C basic data types.
❏ To be able to create and use variables and constants.
❏ To understand input and output concepts.
❏ To be able to use simple input and output statements.
Introduction to the C Language

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2-1 Background
C is a structured programming language. It is
considered a high-level language because it allows the
programmer to concentrate on the problem at hand
and not worry about the machine that the program
will be using. That is another reason why it is used by
software developers whose applications have to run on
many different hardware platforms.

Computer Science: A Structured Programming Approach Using C 3
2-2 C Programs
It's time to write your first C program.
Structure of a C Program
Your First C Program
Comments
The Greeting Program
Topics discussed in this section:

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FIGURE 2-2 Structure of a C Program

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FIGURE 2-3 The Greeting Program

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PROGRAM 2-1 The Greeting Program

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FIGURE 2-4 Examples of Block Comments

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FIGURE 2-5 Examples of Line Comments

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2-3 Identifiers
One feature present in all computer languages is the
identifier. Identifiers allow us to name data and other
objects in the program. Each identified object in the
computer is stored at a unique address.

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Table 2-1 Rules for Identifiers

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An identifier must start with a letter or underscore:
it may not have a space or a hyphen.
Note

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C is a case-sensitive language.
Note

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Table 2-2 Examples of Valid and Invalid Names

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2-4 Types
A type defines a set of values and a set of operations
that can be applied on those values.
Void Type
Integral Type
Floating-Point Types

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sizeof (short) ≤ sizeof (int) ≤ sizeof (long) ≤ sizeof (long long)
Note

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Table 2-3 Typical Integer Sizes and Values for Signed Integers

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FIGURE 2-10 Floating-point Types

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sizeof (float) ≤ sizeof (double) ≤ sizeof (long double)
Note

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2-5 Variables
Variables are named memory locations that have a type,
such as integer or character, which is inherited from
their type. The type determines the values that a variable
may contain and the operations that may be used with
its values.
Variable Declaration
Variable Initialization

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Table 2-5 Examples of Variable Declarations and Definitions

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FIGURE 2-12 Variable Initialization
‘B’

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When a variable is defined, it is not initialized.
We must initialize any variable requiring
prescribed data when the function starts.
Note

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PROGRAM 2-2 Print Sum of Three Numbers

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PROGRAM 2-2 Print Sum of Three Numbers (continued)

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PROGRAM 2-2 Print Sum of Three Numbers (continued)

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2-6 Constants
Constants are data values that cannot be changed
during the execution of a program. Like variables,
constants have a type. In this section, we discuss
Boolean, character, integer, real, complex, and string
constants.
Constant Representation
Coding Constants

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A character constant is enclosed in single quotes.
Note

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Table 2-6 Symbolic Names for Control Characters

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Table 2-7 Examples of Integer Constants

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Table 2-8 Examples of Real Constants

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FIGURE 2-14 Null Characters and Null Strings

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Use single quotes for character constants.
Use double quotes for string constants.
Note

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PROGRAM 2-3 Memory Constants

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PROGRAM 2-3 Memory Constants (continued)

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PROGRAM 2-4 Enumeration Data Type
enum week{sunday, monday, tuesday, wednesday,
thursday, friday, saturday};
enum week day;
LCD Example

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// An example program to demonstrate working
// of enum in C
#include<stdio.h>
enum week{Mon, Tue, Wed, Thur, Fri, Sat, Sun};
int main()
{
enum week day;
day = Wed;
printf("%d",day);
return 0;
}

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#include <stdio.h>
#include <float.h>
int main(){
printf("Storage size for float : %d n", sizeof(float));
printf("Minimum float positive value: %En", FLT_MIN );
printf("Maximum float positive value: %En", FLT_MAX );
printf("Precision value: %dn", FLT_DIG );
return 0;
}

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USER DEFINED (DATA) TYPES
Keyword Size Note
struct
≥ sum of size
of each
member
An aggregate type which can contain more
than one different types.
tag or label is optional
struct theEmployee {
int age;
double salary;
char department;
char name[15];
char address[5][25];
};
struct theEmployee workerRec;
typedef struct
{
int x;
int SomeArray[100];
} MyFoo;
int main()
{
MyFoo strctVar;
return 0;
}
struct newPoint {
short xPoint;
short yPoint;
} justPoint;
justPoint thePoint;

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union
≥ size of the
largest
member
An aggregate type which can contain more than
one other types. union uses shared memory
space compared to struct, so only one member
can be accessed at one time.
union someData
{
int pNum;
float qNum;
double rNum;
};
union someData simpleData;
union OtherData{
char aNum;
int xNum;
float fNum;
} simpleData;
simpleData saveData;

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typedef
same as the type;
being given a new
name
typedef used to give new identifier names or alias (to
simplify the long identifier names), normally used for
aggregate defined types.
typedef unsigned char BYTE; /* Declares BYTE to be a synonym for unsigned char */
typedef float FLOAT; /* Declares FLOAT (uppercase letter) to be a synonym for unsigned float
(lowercase) */
tag or label is optional
typedef struct simpleData
{ int nData;
char cData;
} newNameType;
Or
typedef struct { int nData;
char cData;} newNameType;
newNameType strctType;
typedef struct TOKEN_SOURCE {
CHAR SourceName[8];
LUID SourceIdentifier;
} TOKEN_SOURCE, *PTOKEN_SOURCE;
TOKEN_SOURCE newToken;
typedef union unData{
double lngSalary;
int nDay;
}newUntype;
newUnType lntotalSalary;
typedef enum DayNames { Monday,
Tuesday,
Wednesday,
Thursday,
Friday, Saturday, Sunday
} Weekdays;
Weekdays dayOfWeek;

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Type Size Note
type*
(a pointer)
≥ size of char
 Hold the memory address which point to the
actual data/value.
 0 address always represents the null pointer (an
address where no data can be placed),
irrespective of what bit sequence represents the
value of a null pointer.
 Pointers to different types will have different sizes.
So they are not convertible to one another.
 Even in an implementation which guarantees all
data pointers to be of the same size, function
pointers and data pointers are in general
incompatible with each other.
 For functions taking a variable number of
arguments, the arguments passed must be of
appropriate type.
char *ptoChar;
char csimpleChr = 'T';
char *chptr;
// assignment
chptr = &csimpleChr;
int iNumber = 20;
int *imyPtr = &iNumber;
DERIVED (DATA) TYPES

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DERIVED (DATA) TYPES
type [integer]
(an array)
≥ integer × size of
type
 Use to declare a variable with
collection of identical properties or
types.
 Simplify variable declaration.
 In a declaration which also initializes
the array (including a function
parameter declaration), the size of
the array (the integer) can be
omitted, which is called unsized.
 type [ ] is not the same as type*.
Only under some circumstances one
can be converted to the other.
int fstudentNumber[3] = {4,7,1};
int nrowandColumn[1][2] = {34, 21};
int nlongHeightWidth[3][4][5] = 0;
char cName1[ ] =
{'a','r','r','a','y'};
char cName2[ ] = {"array"};
char cName3[6] = "array";
int nrowCol[2][3] = {4,2,3,7,2,8};

C Programming Intro.ppt

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