Programming construction tools

1. C PROGRAMMING
PROF. SUNIL D. CHUTE
DEPT OF COMPUTER SCIENCE
M.G. ARTS SCI AND LATE N.P. COMMERCE COLLEGE ARMORI

2. PROGRAMMING CONSTRUCTION TOOLS
ALGORITHUM
FLOWCHART

3. Algorithm
What is algorithm?
An algorithm is a procedure or step-by-step instruction for solving a
problem. They form the foundation of writing a program.
For writing any programs, the following has to be known:
Input
Tasks to be preformed
Output expected
For any task, the instructions given to a friend is different from the instructions
given to a computer. Let’s look at the difference between them and know how to
give instructions to a computer.

4. Qualities of Good Algorithms
 Input and output should be defined precisely.
 Each step in the algorithm should be clear and
unambiguous.
 Algorithms should be most effective among many different
ways to solve a problem.
 An algorithm shouldn't include computer code. Instead,
the algorithm should be written in such a way that it can
be used in different programming languages.

5. Algorithm Examples
Algorithm 1: Add two numbers entered by the user
Step 1: Start
Step 2: Declare variables num1, num2 and sum.
Step 3: Read values num1 and num2.
Step 4: Add num1 and num2 and assign the result to sum.
sum←num1+num2
Step 5: Display sum
Step 6: Stop

6. Algorithm 2: Find the largest number
among three numbers
Step 1: Start
Step 2: Declare variables a,b and c.
Step 3: Read variables a,b and c.
Step 4: If a > b If a > c
Display a is the largest number.
Else
Display c is the largest number.
Else If b > c
Display b is the largest number.
Else
Display c is the greatest number.
Step 5: Stop

7. Flowchart
A flowchart is a type of diagram that represents
an algorithm, workflow or process.
The flowchart shows the steps as boxes of
various kinds, and their order by connecting the
boxes with arrows. … Flowcharts are used in
analyzing, designing, documenting or managing a
process or program in various fields.

8. Flowchart Symbols
Flowcharts use special shapes to represent
different types of actions or steps in a
process. Lines and arrows show the sequence
of the steps, and the relationships among
them. These are known as flowchart symbols.

9. Common Flowchart Symbols
 Rectangle Shape – Represents a process
 Oval or Pill Shape – Represents the start or end
 Diamond Shape – Represents a decision
 Parallelogram – Represents input/output

12. DATA TYPES IN C LANGUAGE
 A data type specifies the type of data that a variable can store such as
integer, floating, character, etc.

13. There are the following data types in C
language.
Types Data Types
Basic Data Type int, char, float, double
Derived Data Type array, pointer, structure, union
Enumeration Data Type enum
Void Data Type void

14. Basic Data Types
 The basic data types are integer-based and floating-point based. C language supports
both signed and unsigned literals.
 The memory size of the basic data types may change according to 32 or 64-bit
operating system.
Data Types Memory Size Range
char 1 byte −128 to 127
signed char 1 byte −128 to 127
unsigned char 1 byte 0 to 255
short 2 byte −32,768 to 32,767
signed short 2 byte −32,768 to 32,767
unsigned short 2 byte 0 to 65,535

15. Data Types Memory Size Range
int 2 byte −32,768 to 32,767
signed int 2 byte −32,768 to 32,767
unsigned int 2 byte 0 to 65,535
short int 2 byte −32,768 to 32,767
signed short int 2 byte −32,768 to 32,767
unsigned short int 2 byte 0 to 65,535
long int 4 byte -2,147,483,648 to
2,147,483,647
signed long int 4 byte -2,147,483,648 to
2,147,483,647
unsigned long int 4 byte 0 to 4,294,967,295
float 4 byte
double 8 byte
long double 10 byte

16. Keywords in C
 A keyword is a reserved word. You cannot use it as a variable name,
constant name, etc. There are only 32 reserved words (keywords) in the
C language.
A list of 32 keywords in the c language is given below:
auto break case char const continu
e
default do
double else enum extern float for goto if
int long register return short signed sizeof static
struct switch typedef union unsigne
d
void volatile while

17. Variables in C
 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.
 It is a way to represent memory location through symbol so that it can be easily
identified.
 Let's see the syntax to declare a variable:
Syntax:Datatype variable_list;
The example of declaring the variable is given below:
1. int a;
2. float b;
3. char c;
Here, a, b, c are variables. The int, float, char are the data types.
We can also provide values while declaring the variables as given below:
1. int a=10,b=20;//declaring 2 variable of integer type
2. float f=20.8;
3. char c='A';

18. Rules for defining variables
• A variable can have alphabets, digits, and underscore.
• A variable name can start with the alphabet, and underscore only. It can't
start with a digit.
• No whitespace is allowed within the variable name.
• A variable name must not be any reserved word or keyword, e.g. int, float,
etc.
Valid variable names:
1. int a;
2. int _ab;
3. int a30;
Invalid variable names:
1. int 2;
2. int a b;
3. int long;