Datatype and Operators used in C Programming

DATA TYPES, OPERATORS AND
SOME STATEMENT Prepared by : Er. Rhishav
Poudyal
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 The compiler collects the characters of aprogram
into tokens.
◦ Tokens make up the basic vocabulary of a computer
language.
 The compiler then checks the tokens to see ifthey
can be formed into legal strings according to the
syntax (the grammar rules) of thelanguage.
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2

 Lowercase letters
◦ a b c . . . z
 Uppercase letters
◦ A B C . . . Z
 Digits
◦ 0 1 2 3 4 5 6 7 8 9
 Other characters
◦ + - * / = ( ) { } [ ] < > „ “
◦ ! @ # $ % & _ ^ ~ . , ; : ?
 White space characters
◦ blank, newline, tab, etc.
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 Keywords
 Identifiers
 Constants
 String Constants
 Operators
 Special symbol
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 A 'C' program consist of two types of elements , user defined
and system defined. Identifiers is nothing but a name given to
these elements.
 An identifier is a word used by a programmer to name a
variable , function, or label.
 identifiers consist of letters and digits, in any order, except that
the first character or label.
 Identifiers consist of letters and digits if any order, except that
the first character must be letter.
 Both Upper and lowercase letters can be used
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 Keywords are nothing but
system defined identifiers.
 Keywords are reserved
words of the language.
 They have specific meaning
in the language and cannot
be used by the programmer
as variable or constant
names
 C is case senitive, it means
these must be used as it is
 32 Keywords in C
Programming
auto double int struct
break else long switch
case enum register typedef
char extern return union
const float short unsigned
continue for signed void
default goto sizeof volatile
do if static while
6
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 Variables in C have the same meaning as variables in
algebra. That is, they represent some unknown, or
variable, value.
x = a + b
z + 2 = 3(y - 5)
 Remember that variables in algebra are represented by a
single alphabetic character.
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 Variables in C may be given representations
containing multiple characters. But there are
rules for these representations.
 Variable names in C
◦ May only consist of letters, digits, and underscores
◦ May be as long as you like, but only the first 31
characters are significant
◦ May not begin with a number
◦ May not be a C reserved word (keyword)
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 An identifier is a token:
◦ Composed of a sequence of letters, digits, and the
underscore character _
 Note: Variable names are identifiers
 Lower- and uppercase letters are treated as distinct
(different).
 Identifiers should be chosen so that theycontribute
to the readability and documentation of the
program.
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 main
◦ C programs always begin execution at the function main.
 Identifiers that begin with an underscore shouldbe
used only by systems programmers
◦ Because they can conflict with system names.
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 C programmers generally agree on the following
conventions for naming variables.
◦ Begin variable names with lowercase letters
◦ Use meaningful identifiers
◦ Separate “words” within identifiers with underscores or mixed
upper and lower case.
◦ Examples:
 surfaceArea
 surface_Area
 surface_area
◦ Be consistent!
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(used in
 Use all uppercase for symbolic constants
#define preprocessor directives).
 Examples:
#define PI 3.14159
#defineAGE 52
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 C is case sensitive
◦ It matters whether an identifier, such as a variable name, is
uppercase or lowercase.
◦ Example:
area
Area
AREA
ArEa
are all seen as different variables by the compiler.
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 Legal variable names
ClassSize
_previous_value
Percent
PerCent
PERCENT
Kdff123
kkkkk
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identifiers reasons
savings#account Contains the illegal character #
Double Is a C keyword
rad ius Space is illegal
Tax-Rate - is illegal
union A reserved word
9winter First character is a digit
15
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area_under_the_curve
num45
#values
pi
%done
AREA
3D
Last-Chance
x_yt3
num$
lucky***
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 Integer Constants
◦ 25 and 0
 Floating Constants
◦ 3.14159 and 0.1
 Character Constants
◦ „a‟and „B‟and „+‟and „;‟but not “a” or “B”
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 The backslash is called the escape character.
◦ The newline character „n‟represents a single character
called newline.
◦ Think of n as “escaping” the usual meaning of n.
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 A sequence of characters enclosed in a pair of
double quote marks, such as “abc” is a string
constant, or a string literal.
 Character sequences that would have meaning if
outside a string constant are just a sequence of
characters when surrounded by double quotes.
 String constants are treated by the compileras
tokens and the compiler provides the space in
memory to store them.
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 Before using a variable, you must give the compiler
some information about the variable; i.e., you must
declare it.
 The declaration statement includes the data typeof
the variable.
 Examples of variable declarations:
int balls ;
float area ;
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There are five basic data types associated with
variables:
 int - integer: a whole number.
 float - floating point value: ie a number with
a fractional part.
 double - a double-precision floating point
value.
 char - a single character.
 void - valueless special purpose type
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A Data type or simply type is a classification of
data which tells the compiler or interpreter
how the programmer intends to use the data
 Primary Data Types(Fundamental Data Types)
Integer: int -32,768 to 32,768.
Character: char -128 to 127.
Floating Point: float 3.4e-38 to 3.4e+38.
Double Precision Floating Point: double 1.7e-
308 to 1.7e+308.
Void Data Type: void (used for function when
no value is to be return)
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A Data Type
 A data type is
 A set of values AND
 A set of operations on those values
 A data type is used to
 Identify the type of a variable when the variable is declared
 Identify the type of the return value of a function
 Identify the type of a parameter expected by a function
VARIABLES ,INPUT AND
OUTPUT 24
Prepared by :Er. Rhishav Poudyal

A Data Type (continued)
 When the compiler encounters a declaration for a variable,
it sets up a memory location for it
 An operator used on a variable or variables is legal only if
 The operator is defined in that programming language for a
variable of that type
 The variable or variables involved with the operator are of the
same or compatible types
OUTPUT 25

Two Classifications of Data Types
 Built-in data types
 Fundamental data types (int, char, double, float,
void, pointer)
 Derived data types (array, string, structure)
 Programmer-defined data types
 Structure
 Union
 Enumeration
OUTPUT 26

OUTPUT 27

Data types in C
Only really four basic types:
 char
 int (short, long, long long, unsigned)
 float
 double
Type Size (bytes)
char 1
int 4
short 2
long 4
long long 8
float 4
double 8
OUTPUT 28

Fundamental Data Types
 void – used to denote the type with no values
 int – used to denote an integer type
 char – used to denote a character type
 float, double – used to denote a floating point
type
 int *, float *, char * – used to denote a pointer
type, which is a memory address type
OUTPUT 29

FIGURE Integer Types
OUTPUT 30

sizeof (short) ≤ sizeof (int) ≤ sizeof (long) ≤ sizeof (long long)
Note
OUTPUT 31

Table Typical Integer Sizes and Values for Signed Integers
OUTPUT 32

FIGURE Floating-point Types
OUTPUT 33

sizeof (float) ≤ sizeof (double) ≤ sizeof (long double)
Note
OUTPUT 34

Characters (char)
 Roman alphabet, punctuation, digits, and other
symbols:
 Encoded within one byte (256 possible symbols)
 ASCII encoding
 In C:
char a_char = ’a’;
char newline_char = ’n’;
char tab_char = ’t’;
char backslash_char = ’’;
OUTPUT 35

ASCII
From “man ascii”:
| 0 NUL| 1 SOH| 2 STX| 3 ETX| 4 EOT| 5 ENQ| 6 ACK| 7 BEL|
| 8 BS | 9 HT | 10 NL | 11 VT | 12 NP | 13 CR | 14 SO | 15 SI |
| 16 DLE| 17 DC1| 18 DC2| 19 DC3| 20 DC4| 21 NAK| 22 SYN| 23 ETB|
| 24 CAN| 25 EM | 26 SUB| 27 ESC| 28 FS | 29 GS | 30 RS | 31 US |
| 32 SP | 33 ! | 34 " | 35 # | 36 $ | 37 % | 38 & | 39 ' |
| 40 ( | 41 ) | 42 * | 43 + | 44 , | 45 - | 46 . | 47 / |
| 48 0 | 49 1 | 50 2 | 51 3 | 52 4 | 53 5 | 54 6 | 55 7 |
| 56 8 | 57 9 | 58 : | 59 ; | 60 < | 61 = | 62 > | 63 ? |
| 64 @ | 65 A | 66 B | 67 C | 68 D | 69 E | 70 F | 71 G |
| 72 H | 73 I | 74 J | 75 K | 76 L | 77 M | 78 N | 79 O |
| 80 P | 81 Q | 82 R | 83 S | 84 T | 85 U | 86 V | 87 W |
| 88 X | 89 Y | 90 Z | 91 [ | 92 | 93 ] | 94 ^ | 95 _ |
| 96 ` | 97 a | 98 b | 99 c |100 d |101 e |102 f |103 g |
|104 h |105 i |106 j |107 k |108 l |109 m |110 n |111 o |
|112 p |113 q |114 r |115 s |116 t |117 u |118 v |119 w |
|120 x |121 y |122 z |123 { |124 | |125 } |126 ~ |127 DEL|
Special
control
characters
OUTPUT 36

 When we declare a variable
◦ Space is set aside in memory to hold a value of the specified
data type
◦ That space is associated with the variable name
◦ That space is associated with a unique address
 Visualization of the declaration
int balls ;
balls
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FE07
garbage

C has three basic predefined data types:
 Integers (whole numbers)
◦ int, long int, short int, unsigned int
 Floating point (real numbers)
◦ float, double
 Characters
◦ char
 At this point, you need only be concerned with
the data types that are bolded.
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 Variables may be be given initial values, or initialized,
when declared. Examples:
int length = 7 ;
float diameter = 5.9 ;
char initial = „A‟;
7
5.9
„A‟
length
diameter
initial
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 Do not “hide” the initialization
◦ put initialized variables on a separate line
◦ a comment is always a good idea
◦ Example:
/* rectangle height */
int height ;
int width = 6 ;
int area ;
/* rectangle width */
/* rectangle area */
NOT int height, width = 6, area ;
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 Variables may have values assigned to them throughthe
use of an assignment statement.
 Such a statement uses the assignment operator =
 This operator does not denote equality. It assigns the
value of the righthand side of the statement (the
expression) to the variable on the lefthandside.
 Examples:
diameter = 5.9 ;
area = length * width ;
Note that only single variables may appear on thelefthand
side of the assignment operator.
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#include <stdio.h>
int main( )
{
int inches, feet, fathoms ;
fathoms = 7 ;
feet = 6 * fathoms ;
inches = 12 * feet ;



inches
feet
fathoms
garbage
fathoms
7
garbage
feet
42
garbage
504
inches
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In order to use these characters, escape sequence is used.
 Escape Sequences Character
 b
 f
 n
 r
 t
 v

 '
 "
 ?
 0
Backspace
Form feed
Newline
Return
Horizontal tab
Vertical tab
Backslash
Single quotation mark
Double quotation mark
Question mark
Null character
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 Operator
 +
 -
 *
 /
 %
Meaning of Operator
addition or unary plus
subtraction or unary minus
multiplication
division
remainder after division( modulo division)
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Operator example Meaning
+ a + b Addition –unary
- a – b Subtraction- unary
* a * b Multiplication
/ a / b Division
% a % b Modulo division- remainder
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 An assignment operator is used for assigning a value
to a variable. The most common assignment operator
is =
 Operator
 =
 +=
 -=
 *=
 /=
 %=
Example
a = b
a += b
a -= b
a *= b
a /= b
a %= b
Same as
a = b
a = a+b
a = a-b
a = a*b
a = a/b
a = a%b
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Operator Meaning
< Is less than
<= Is less than or equal to
> Is greater than
>= Is greater than or equal to
== Equal to
!= Not equal to
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 A relational operator checks the relationship between two
operands. If the relation is true, it returns 1; if the relation
is false, it returns value 0.
 Relational operators are used in decision making and
loops.
Operator Meaning of Operator Example
 == Equal to 5 == 3 returns 0
 > Greater than 5 > 3 returns 1
 < Less than 5 < 3 returns 0
 != Not equal to 5 != 3 returns 1
 >= Greater than or equal to 5 >= 3 returns 1
 <= Less than or equal to 5 <= 3 return 0
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Logical Operators
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Operator Meaning
&& Logical AND
|| Logical OR
! Logical NOT
Logical expression or a compound relational
expression-
An expression that combines two or more relational
expressions
Ex: if (a==b && b==c)

C supports 2 useful operatorsnamely
1. Increment ++
2. Decrement -- operators
The ++ operator adds a value 1 to the operand
The – operator subtracts 1 from the operand
++a or a++
--a or a--
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Let the value of a =5 and b=++a then
a = b =6
Let the value of a = 5 and b=a++ then
a =5 but b=6
i.e.:
1.a prefix operator first adds 1 to the operand and then
the result is assigned to the variable on theleft
2.a postfix operator first assigns the value to the
variable on left and then increments the operand.
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Syntax: exp1 ? exp2 : exp3
Where exp1,exp2 and exp3 are expressions
Working of the ? Operator:
Exp1 is evaluated first, if it is nonzero(1/true) then the
expression2 is evaluated and this becomes the value of
the expression,
If exp1 is false(0/zero) exp3 is evaluated and its value
becomes the value of the expression
Ex: m=2;
n=3
r=(m>n) ? m : n;
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These operators allow manipulation of data at the bit level
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Operator Meaning
& Bitwise AND
| Bitwise OR
^ Bitwise exclusive OR
<< Shift left
>> Shift right

& bitwise AND
| bitwise OR
^ bitwise XOR
~ 1‟s compliment
<< Shift left
>> Shift right
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All these operators can be suffixed with =
For instance a &= b; is the same as a = a & b;

a b a&b a|b a^b ~a
0 0 0 0 0 1
0 1 0 1 1 1
1 0 0 1 1 0
1 1 1 1 0 0
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• The other bitwise operators are:
~ bitwise not
& bitwise and
^ bitwise xor
| bitwise or
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Algebraic expression C expression
ab-c a*b-c
(m+n)(x+y) (m+n)*(x+y)
ab
c
a*b/c
3x2+2x+1 3*x*x+2*x+1
a
b
a/b
S= a  b  c
2
S=(a+b+c)/2
Chapter 3: DATA TYPES,OPERATORS
AND SOME STATEMENT
Prepared by : Er. Rhishav
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Algebraic expression C expression
area= s(sa)(sb)(sc) area=sqrt(s*(s-a)*(s-b)*(s-c))
Sin  b 
 
 a 2
 b2

sin(b/sqrt(a*a+b*b))
1 
x  y 
xy2

2

 
tow1=sqrt((rowx-rowy)/2+tow*x*y*y)
1 
  
2

x y
 xy2
 2 
tow1=sqrt(pow((rowx-rowy)/2,2)+tow*x*y*y)
y 
    x
sin
y=(alpha+beta)/sin(theta*3.1416/180)+abs(x)
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BODMAS RULE-
Brackets of Division Multiplication Addition Subtraction
Brackets will have the highest precedence and have to be
evaluated first, then comes of , then comes division,
multiplication, addition and finally subtraction.
The 2 distinct priority levels of arithmetic operators in c
are-
Highest priority : * / %
Lowest priority : + -
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1. First parenthesized sub expression from left to right are
evaluated.
2. If parentheses are nested, the evaluation begins with the
innermost sub expression
3. The precedence rule is applied in determining the order of
application of operators in evaluating sub expressions
4. The associatively rule is applied when 2 or more operators
of the same precedence level appear in a sub expression.
5. Arithmetic expressions are evaluated from left to right using
the rules of precedence
6. When parentheses are used, the expressions within
parentheses assume highest priority
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Operator Description Associativity
( ), [ ] Function call, array
element reference
Left to Right
+, -, ++, - -
,!,~,*,&
Unary plus, minus,
increment, decrement,
logical negation, 1’s
complement, pointer
reference, address
Right to Left
*, / , % Multiplication,
division, modulus
Left to Right
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Precedence Associativity
( )
* / %
+ (addition) - (subtraction)
< <= > >=
== !=
&&
||
left to right/inside-out
left to right
left to right
left to right
left to right
left to right
left to right
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Evaluate x1=(-b+ sqrt (b*b-4*a*c))/(2*a) @ a=1,
b=-5, c=6
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Evaluate x1=(-b+ sqrt (b*b-4*a*c))/(2*a) @ a=1,
b=-5, c=6
=(-(-5)+sqrt((-5)(-5)-4*1*6))/(2*1)
=(5 + sqrt((-5)(-5)-4*1*6))/(2*1)
=(5 + sqrt(25 -4*1*6))/(2*1)
=(5 + sqrt(25 -4*6))/(2*1)
=(5 + sqrt(25 -24))/(2*1)
=(5 + sqrt(1))/(2*1)
=(5 + 1.0)/(2*1)
=(6.0)/(2*1)
=6.0/2 = 3.0
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Given
int a = 5, b = 7, c = 17 ;
evaluate each expression as True or False.
1. c / b == 2
2. c % b <= a % b
3. b + c / a != c - a
4. (b < c) && (c == 7)
5. (c + 1 - b == 0) || (b = 5)
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Variable Scope
 When you declare a variable, that name and value is only
“alive” for some parts of the program
 We must declare variables before we use them, so the
scope of a variable starts when it is declared
 If the variable is declared within a block (compound
statement, { } ) it only stays alive until the end of the
block
If the block is the one surrounding the entire
function body, the variable is alive from where it is
declared until the end of the function
If the block defines a loop body or if-statement
body, the variable only lives till the end of loop/if
You can add a block anywhere you want in the code,
and it will define the scope for any variables
declared within it
OUTPUT 67

Variable Scope
 Example scopes
int main ( ) {
int i;
for (i=0; i < 10; i++ ) {
int total = i;
}
int j = total; // error! total out of scope
{
int k;
// use k
}
int m = j;
…
}
i
j
m
total
k
OUTPUT 68

Variable Scope
 In C, we can reuse names, as long as they are not in
overlapping scopes
 In fact, we can reuse names in a scope which is nested
inside another scope
int main ( ) {
int i = 5, j = 0;
for (j = 0; j < 10; j++) {
int i = j; // OK, this is new i
int k = 5;
doSomething (i);
}
int sum = k; // compile error, no k in scope
j = i; // sets j to 5
for (j = 0; j < 100; j++ ) {
int i = j; // yet another new i
}
int i = 0; // compile error –redefined variable
}
OUTPUT 69

Variable Scope
 All local scope defined by blocks
 There is another kind of scope, called global scope
 This is for variables defined outside of functions
 Global variables have scope from the point they are
defined throughout the rest of file
 Local variables of same name can be nested inside global
variables
int total = 5;
int main ( ) {
int total = 4; // OK, this is nested scope
….
}
int sub1 ( ) {
int i = total; // OK, i set to 5
}
OUTPUT 70

Variable Scope
 Style rules
 Try to minimize scope
 Only use global variables if you really, really have
to !!!
 2 different approaches for local variables inside a
function
1. Declare all variables at the top of the function
• This is the way you used to have to do it in C
• Helps the reader to know where to look for the
variable declaration
2. Declare variables as they are needed
• Minimizes scope
• Allows you to set the value only once, rather then
once at declaration and then again at first use
 Either approach is OK – probably the most common in
industry is to declare as needed
 Don’t re-use names heavily, except for maybe i, j, k
OUTPUT 71

PROGRAM Print Sum of Three Numbers
OUTPUT 72

PROGRAM Print Sum of Three Numbers (continued)
OUTPUT 73

PROGRAM Print Sum of Three Numbers (continued)
OUTPUT 74

 Failure to correctly terminate a comment.
 Leaving off a closing double quote character at the end
of a string.
 Misspelling or not declaring a variable.
 Misspelling a function name.
 Omitting the ampersand (&) with
scanf( ).
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/* This is a comment */
//This is also a comment
The compiler first replaces each comment with a
single blank.
Thereafter, the compiler either disregardswhite
space or uses it to separate tokens.
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 Single line of comment: // comment here
 More than single line of comment or expanded: /*
comment(s) here */
// for printf()
#include <stdio.h>
#include <string.h> // for strcpy_s() and their family
/* main() function, where program
execution starts */
int main()
{
/* declares variable and initializes it*/
int i = 8;
…
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 Syntax (Compile -Time) Errors
◦ Syntax errors are caught by the compiler.
◦ The compiler attempts to identify the error and display
a helpful error message.
 Run-Time Errors
◦ Errors that occur during program execution.
◦ Memory errors caused by not using the address operator
& with a scanf ( ) argument.
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 Use white space and comments to make your code easier
to read and understand.
◦ Indent logical subgroups of code by 3 spaces.
 Choose variable names that convey their use in the
program.
 Place all #include, #define, main(), and braces { } -- that
begin and end the body of a function.
Poudyal
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Datatype and Operators used in C Programming

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