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1. Dr A GNANABASKARAN
Content by
C Programming- Basics of C

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Software Development Life Cycle

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Logical Building
 Logic building skills are essential for programs.
 Logic building is the process of developing logical thinking and problem-solving skills.
 If one wishes to be a programmer, he or she needs to keep getting better at developing logic.
 Complex and sophisticated algorithms require advanced logic in order for programmers to work with
them.
 Developers must also learn about data structures, algorithms and programming paradigms.
 Another requisite for acquiring logic building skills is being comfortable with solving problems daily.

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Logical Building

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Logical Building

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Enhancing Programming Logic
 Practice writing a lot of code
 Check solutions by other people
 Work out solutions
 Keep learning new things
 Be consistent
 Face problems head-on

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Features of C

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Structure of C Program

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Structure of C Program

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 #include <stdio.h>
 #include <math.h>
 #include <conio.h>
 #include <string.h>
Header Files

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Commonly used Predefined Functions
 main()
 printf()
 scanf()
 Note:
1. Every C statement ends with a semicolon ;
2. The body of int main() could also been written as:
int main(){printf("Hello World!");return 0;}
3. The compiler ignores white spaces. However, multiple lines makes the code more readable.

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Escape Sequences
Escape Sequence Description
t Creates a horizontal tab
n Creates a new line
v Creates a vertical tab

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C Comments
Single-line Comments
 comments start with two forward slashes (//).
C Multi-line Comments
 comments start with /* and ends with */.
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DataTypes
 Data types refer to the type of data that we are using in a C program.
 Whenever we utilize a data type in a C program, we define the variables or functions
used in it.
 the type of data that is in use, so that the compiler knows exactly what type of data
it must expect from the given program.
 must use a format specifier
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 Data types used in C language refer to an extensive system that we use to declare
various types of functions or variables in a program.
 the space that it occupies in storage, along with the way in which the stored bit
pattern will be interpreted
Purpose of DataTypes
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Types of DataTypes
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DataType Example of DataType
Primary Data types Floating-point, integer, double, character.
Derived DataTypes Union, structure, array, etc.
Enumerated DataTypes Enum
Void DataType EmptyValue
Bool Type True or False

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Enumeration (or enum)
 Enumeration (or enum) is a user defined data type in C.
 It is mainly used to assign names to integral constants, the names make a program
easy to read and maintain
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20. Enum
#include<stdio.h>
int main()
{
enum colour { green, red=5, blue, white, yellow=10, pink };
printf("%d %d %d %d %d %d", green, red, blue, white, yellow, pink);
return 0;
}
Output:
0 5 6 7 10 11

21. Enum
#include<stdio.h>
enum test{A=32766,B,C};
int main()
{
printf("%d %d %d",A,B,C);
return 0;
}
Output:
32766 32767 32768

22. Enum
#include<stdio.h>
enum color{RED=5,GREEN,YELLOW,BLACK}
c;
int main()
{
for(c=RED;c<=BLACK;c++)
{
printf("ctutorial.blogspot.comn");
}
return 0;
}
Output:

23. Primary DataTypes
Keyword Used DataType Memory Allocation
int Integer 2 bytes/4 bytes
float Floating-point 4 bytes
void Void 0 byte
char Character 1 byte
double Double 8 bytes

24. DataType Modifiers
 data types much more specific
Here are a few modifiers:
 short
 long
 unsigned
 signed

25. Range of Values of C DataType
25
DataType Format Specifier Minimal Range Typical Bit Size
unsigned char %c 0 to 255 8
char %c -127 to 127 8
signed char %c -127 to 127 8
int %d, %i -32,767 to 32,767 16 or 32
unsigned int %u 0 to 65,535 16 or 32
signed int %d, %i Same as int Same as int
16 or 32
short int %hd -32,767 to 32,767 16

26. Range of Values of C DataType
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DataType Format Specifier Minimal Range Typical Bit Size
unsigned short int %hu 0 to 65,535 16
signed short int %hd Same as short int 16
long int %ld, %li -2,147,483,647 to
2,147,483,647
32
long long int %lld, %lli -(263 – 1) to 263 – 1 (It
will be added by the C99
standard)
64
signed long int %ld, %li Same as long int 32
unsigned long int %lu 0 to 4,294,967,295 32
unsigned long
long int
%llu 264 – 1 (It will be added
by the C99 standard)
64

27. Range of Values of C DataType
27
float %f 1E-37 to 1E+37 along with six digits of the
precisions here
32
double %lf 1E-37 to 1E+37 along with six digits of the
precisions here
64
long double %Lf 1E-37 to 1E+37 along with six digits of the
precisions here
80

28. Out of Range
 #include <stdio.h>
 int main()
 {
 // the maximum value allowed in the signed short int is 32767
 signed short int x = 34767;
 return 0;
 }
 The generated output for this program would be:
 warning: very large integer value implicitly truncated to signed type [-Woverflow]
 signed short int x = 34767;
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29. Keywords / Reserved Words
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30. Variables
 A variable is a name of the memory location.
 It is used to store data. Its value can be changed, and it can be reused many times.
 Syntax:
 type variable_list;
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Valid variable names: Invalid variable names:
int a;
int _ab;
int a30;
int 2;
int a b;
int long;

31. Types of Variables in C
 Local Variable
 GlobalVariable
 Static Variable
 AutomaticVariable
 External Variable
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LocalVariable
 A variable that is declared inside the function or block is called a local variable.
 It must be declared at the start of the block.
 Example:
void function1()
{
int x=10;//local variable
}

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LocalVariable
int function1()
{
int x=10;//local variable
return x;
}
main()
{
printf(“%d”,function1());
return 0;
}

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GlobalVariable
 A variable that is declared outside the function or block is called a global variable.
 Any function can change the value of the global variable. It is available to all the functions.
 It must be declared at the start of the block.
 Example:
int value=20;//global variable
void function1()
{
int x=10;//local variable
}

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GlobalVariable
#include <stdio.h>
int count = 0;
void my_function()
{
count++;
printf("Function called %d timesn", count);
}
int main()
{
my_function();
my_function();
my_function();
return 0;
}

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Static Variable
 A variable that is declared with the static keyword is called static variable.
 It retains its value between multiple function calls.
#include <stdio.h>
int main()
{
printf("%d",func());
printf("n%d",func());
return 0;
}
int func()
{
static int count=0;
count++;
return count;
}

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Automatic Variable
 All variables in C that are declared inside the block, are automatic variables by
default.We can explicitly declare an automatic variable using auto keyword.
 Example:
void main()
{
int x=10;//local variable (also automatic)
auto int y=20;//automatic variable
}

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External Variable
 a variable in multiple C source files by using an external variable.To declare an external variable,
you need to use extern keyword.
 extern int x=10;//external variable (also global)
 Note: extern only declares the variable but it doesn't allocate any memory for this variable.
 program1.c
 #include "myfile.h"
 #include <stdio.h>
 void printValue()
 {
 printf("Global variable: %d", global_variable);
 }

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Storage Classes in C

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