C programming part2

C_Programming
Part 2
ENG. KEROLES SHENOUDA
1

Features of C
- Simple, versatile, general purpose language
- Programs are fast and efficient
- Has got rich set of operators
- more general and has no restrictions
- can easily manipulates with bits, bytes and addresses
- Varieties of data types are available
- separate compilation of functions is possible and such functions can be called
by any C program
- block-structured language
- Can be applied in System programming areas like operating systems, compilers
& Interpreters, Assemblers etc.,
3

Comments
 Sometimes programmers need
to add some notes beside their
code. Those notes are very
important to describe the code
and to clarify complex operation.
Notes or comments can be
added in two ways as shown in
the following example.
5

Data Types 6
Primitive/Basic TypesDerived
User Defined
enum typedef
Arrays
structure union
pointer Integer ValuesReal Values
signedunsigned

Integer Values 7
long long 8 –9,223,372,036,854,775,808 to
9,223,372,036,854,775,807
unsigned long long 8 0 to 18,446,744,073,709,551,615
Unsigned Integer
0 >>> (2 -1)
size_in_bits
Signed Integer
-(2)
(size_in_bits-1)
>>> +(2 -1)
(size_in_bits-1)

For example “char” 8
For example if the Unsigned charvalue uses one byte (8 bits) to
hold the numeric value:
Another example if the Signed char value uses one byte (8 bits)
to hold the numeric
value. If Tow‟s Complement method is used to represent the
negative values:

For example “char” 9
For example if the Unsigned short value uses one byte (16 bits)
to hold the numeric value:
Another example if the Signed Integer value uses four byte (32 bits) to hold
the numeric
value. If Tow‟s Complement method is used to represent the negative values:

Note
int, this data type called the machine dependent data type, which means its
size and range
vary from a machine type to another machine type (EX: in 8 bit computers int
is 1 byte, in
16 bit computers int is 2 bytes, in 32 bit computers int is 4 bytes, in 64 bit
computers int is 8
bytes).
Know that (32 Bits computers) means the principle data unit size in those
computers are 32
bit, which mean the computer is designed and optimized to process 32 bit
values
10

Floating-Point Types
Type Storage size Value range Precision
float 4 byte 1.2E-38 to
3.4E+38
6 decimal
places
double 8 byte 2.3E-308 to
1.7E+308
15 decimal
places
long double 10 byte 3.4E-4932 to
1.1E+4932
19 decimal
places
11

IEEE-754 32-bit Single-Precision
Floating-Point Numbers
 In 32-bit single-precision floating-point representation:
 The most significant bit is the sign bit (S), with 0 for positive numbers and 1 for
negative numbers.
 The following 8 bits represent exponent (E).
 The remaining 23 bits represents fraction (F).
12

Example 1: Suppose that IEEE-754 32-bit floating-point representation
pattern is 0 10000000 110 0000 0000 0000 0000 0000.
 Sign bit S = 0 ⇒ positive number
 E = 1000 0000B = 128D (in normalized form)
 Fraction is 1.11B (with an implicit leading 1) = 1 + 1×2^-1 + 1×2^-2 = 1.75D
 The number is +1.75 × 2^(128-127) = +3.5D
13

Example 2: Suppose that IEEE-754 32-bit floating-point representation
pattern is 1 01111110 100 0000 0000 0000 0000 0000.
 Sign bit S = 1 ⇒ negative number
 E = 0111 1110B = 126D (in normalized form)
 Fraction is 1.1B (with an implicit leading 1) = 1 + 2^-1 = 1.5D
 The number is -1.5 × 2^(126-127) = -0.75D
14

C Programming Input Output (I/O):
printf() and scanf()
 C programming has several in-built library functions to perform input and
output tasks.
 Two commonly used functions for I/O (Input/Output) are printf() and scanf().
 The scanf() function reads formatted input from standard input (keyboard)
whereas the printf() function sends formatted output to the standard output
(screen).
16

Eclipse's terminal emulator issue with
scanf()
 Eclipse's terminal emulator
might be different and do
more buffering. Try calling
fflush(stdout); between the
printout and the call to
scanf().
18

int printf( const char* format, ... );%
c
s
d
i
o
x
X
u
f
F
e
E
g
G
*
%10s
%-10s
.4s
20
%
writes a single character.
writes a single character.
converts a signed integer into decimal
converts a unsigned integer into octal representation
converts an unsigned integer into hexadecimal representation
converts an unsigned integer into decimal representation
converts floating-point number to the decimal notation
converts floating-point number to the decimal “Scientific”
converts floating-point number to
"Special values
Take from , …..
Shift 10-string’s length places then print the string
Print the string then shift to 10-string’s length places
Print only 4 char from string

int printf( const char* format, ... ); 21

Data Conversion and Type Casting 29

 The conversion from larger to smaller data
types may lead to some data losses. For that
reason the compiler warns you against this
type of operation. However sometimes the
conversion does not affect the data like the
second expression (b = y). Compiler is not able
to
differentiate between safe or unsafe situation,
for that reason you must use the type casting
to force the conversion if you decide that it is
safe.

Mathematical and Logical Expressions 32

Coding Convention
 Coding convention is a set of rules that enhance the readability and the
understandability of
the code. At the end of each chapter a list of standard and related coding
convention is
mentioned.
35

Generally following roles must be obeyed to
write an arranged code.
37

Follow Chapter 2:
Controlling Program
Flow
C PROGRAMMING FOR ENGINEERS, DR. MOHAMED SOBH
38

References 39
 The Case for Learning C as Your First Programming Language
 A Tutorial on Data Representation
 std::printf, std::fprintf, std::sprintf, std::snprintf…..
 C Programming for Engineers, Dr. Mohamed Sobh

C programming part2

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