The document provides an introduction to C++ programming including definitions of key concepts like compilers, variables, data types, operators, and common errors. It discusses rules for naming variables in C++ and different types of errors like syntax errors, semantic errors, type errors, runtime errors, and logical errors. Code snippets demonstrating these concepts are provided along with examples of errors. Best practices for programming and naming conventions are also outlined.

1. Hello World!
Getting Started with C++
January 13, 2021
Mansi Sharma (Mentor, DSA)
Garima (Project Coordinator, DSA)
(Developer Students Club IGDTUW)

2. A compiler is a special program that
processes statements written in a
particular programming language and turns
them into machine language or "code" that
a computer's processor uses.
COMPILER

3. FIRST PROGRAM
#include<iostream>
using namespace std;
int main () {
cout << "Hello World";
}

4. VARIABLES
A variable is a name given to a memory location. It is the
basic unit of storage in a program.
•The value stored in a variable can be changed during
program execution.
•A variable is only a name given to a memory location, all
the operations done on the variable effects that memory
location.
•In C++, all the variables must be declared before use.

5. RULES FOR NAMING VARIABLES IN C++
• Variable names in C++ can range from 1 to 255
characters.
• All variable names must begin with a letter of the
alphabet or an underscore(_).
• After the first initial letter, variable names can also
contain letters and numbers.
• Variable names are case sensitive.
• No spaces or special characters are allowed.
• You cannot use a C++ keyword (a reserved word) as a
variable name.

6. In C++, data types are declarations for variables. This
determines the type and size of data associated with
variables.
DATATYPES

7. IDENTIFIERS
The C++ identifier is a name used to identify a
variable, function, class, module, or any other user-
defined item. An identifier starts with a letter A to Z
or a to z or an underscore (_) followed by zero or
more letters, underscores, and digits (0 to 9)

8. KEYWORDS IN C++
A keyword is a reserved word. You cannot use it as a variable
name, constant name etc. A list of 32 Keywords in C++
auto break case char const continue default do
double else enum extern float for goto if
int long register return short signed sizeof static
struct switch typedef union unsigned void volatile while

9. OPERATORS IN C++
An operator is a symbol that tells the compiler to perform
specific mathematical or logical manipulations. C++ is rich in
built-in operators and provide the following types of operators −
• Arithmetic Operators
• Relational Operators
• Logical Operators
• Bitwise Operators
• Assignment Operators

10. Types of Errors
Syntax Errors
● These are generated when C++ grammatical rules are violated. Example, missing
semicolon, incorrect operators in cin and cout, compound statement {} missing,
etc.
● Shown at the time of compilation
#include<iostream>
using namespace std;
void main()
{
int x = 10;
int y = 15;
cout << x << y // semicolon missed
}

11. Semantic Errors
● These are generated when C++ statements become meaningless. Example:
b + c = a (expressions don't generate value for variables).
● Value is not assigned to expressions
#include<iostream>
using namespace std;
void main()
{
int a, b, c;
a + b = c; // semantic error
}
error: lvalue required as left operand of assignment
a + b = c; //semantic error

12. Type Errors
● These are generated when a variable is assigned wrong data type. Example: int
value into string.
● Shown at the time of compilation.
#include<iostream>
using namespace std;
void main()
{
int x = "hello"; // type error
}

13. Runtime Errors
● These are generated at the time of execution of program. Example: file not found,
division by zero.
● Shown at run time
#include<iostream>
using namespace std;
void main()
{
int x = 10;
int y = 0;
cout << x / y; // division by zero
}

14. Logical Errors
● These errors cause a program to generate wrong output.
● Maybe your understanding of the underlying program is flawed; maybe you didn’t
write what you thought you wrote. Example: wrong formula for Simple Interest.
#include<iostream>
using namespace std;
void main()
{
int principal = 1000, rate = 2, time = 1 ;
int si = principal * rate * 100 / time; // wrong formula
cout << si;
}

15. Find errors in the
following code
snippets
int main()
{
int i = 10; j = 5;
int modResult = 0;
int divResult = 0;
modResult = i % j;
cout << modResult << " ";
divResult = i / modResult;
cout << divResult;
return 0;
}

16. #include<iostream>
using namespace std;
void main()
{
cout << 'C++ Programming
questions';
int x = 10, y = 5;
int ans = x / (y - y);
cout << ans
return 0;
}
#include<iostream>
using namespace std;
void main()
{
a,b,s int;
d float;
cout<<"The end of the
program";
return 0;
}

17. Wisdom of the Wizards
Programs must be
written for people to
read, and only
incidentally for
machines to execute.
Any fool can write code
that a computer can
understand. Good
programmers write
code that humans can
understand.
Minimise time
needed by someone
else to understand a
piece of your code.
Remember that
someone else may be
you, six months after
writing the code.

18. Naming is 90% of Programming
● Separate names for readability with underscores or hyphens or capitalization
● Coding standards apply
● Use is and has as boolean name prefixes
● Avoid negative names
● Add necessary detail in name: response_time_ms
● Avoid ambiguity: bool read_file, no_items

19. Practice Questions
Question 1
Write a program to input marks of five
subjects and calculate average.
Question 2
Write a program to enter temperature in degree
fahrenheit and change it into degree celcius.
Question 3
Write a program to enter three numbers and
find greatest number using ternary operators.
Question 4
Write a program to enter two numbers and
swap their values.

20. Thank You!