Containers for storing data values are Variables. The different types of variables are as follows:
- int- it stores the integers (whole numbers) without decimals. Ex. 245, -678
- double- it stores the floating point numbers, with decimals. For ex. 18.25 or -18.25. Upto 15 digit decimal point will be executed.
- char- stores single characters, such as ‘b’ or ‘C’. However, it can also be surrounded by double quotes.
- string – it usually stores text, such as “ Hello World”. These values are surrounded by double quotes.
- bool- values are stored with two states either true(1) or false(0).
Declaring or Creating Variables
To create a variable, its type should be specified and value should be assigned.
Syntax: type variableName = value;
where type is C# type( such as int or string), and variableName is name of variable( such as b or name). Equal sign is used to assign values to the variable.
Example
string name = “FindAndSolve”;
Console.WriteLine(name);
output
FindAndSolve
Constants
The const keyword is useful for always storing same value, so our code won’t get messed up. Example: PI(3.1415…).
const int myNum = 124;
myNum = 1347; // error
Note: A constant variable cannot be declared without assigning a value. Otherwise, an error will occur.
Display Variables
WriteLine() method is used to display values of variable to console window. To combine both text and variable, + character should be used.
Example
string name = "FindAndSolve";
Console.WriteLine("Hello " + name);
output
Hello FindAndSolve
You can also use the + character to add a variable to another variable:
Example
string firstName = "FindAndSolve";
string lastName = "Online Tutorial";
string fullName = firstName + lastName;
Console.WriteLine(fullName);
output
FindAndSolve Online Tutorial
For numeric values, the + character works as a mathematical operator (notice that we use int (integer) variables here):
Example
int x = 10;
int y = 7;
Console.WriteLine(x + y); // Print the value of x + y
output
17
From the example above, you can expect:
- x stores the value 10
- y stores the value 7
- Then we use the WriteLine() method to display the value of x + y, which is 17.
Declaring Many Variables
To declare more than one variable of the same type, use a comma-separated list:
Example
int x = 7, y = 8, z = 15;
Console.WriteLine(x + y + z);
output
30
C# Identifiers
All C# variables must be identified with unique names called identifiers. It can be short names ( a and b) or more descriptive names( age, sum, totalVolume).
Note: To create the code which is understand and maintained, it is recommended to use descriptive names.
Example
// Good int minutesPerHour = 60;
// OK, but not so easy to understand what m actually is int m = 60;
General rules for naming variables:
- Names contain digits, letters, underscore character(_)
- Must begin with a letter.
- Should start with a lowercase letter and cannot contain whitespace.
- These are case sensitive(“myVar” and “myvar” are different variables)
- Reserved words ( like C# keywords, such as int or double) can’t be used as names.
A variable in C# is a container to store a value of a specific type, such as int, string, double, etc. Variables can be declared using the syntax <type> <variable_name>
, and values can be assigned using =
. Examples:
C#int age = 30;
string name = "John";
double pi = 3.14;
Scope of variables in C#
In C#, the scope of a variable determines where in the code the variable can be accessed and used. There are two types of scope in C#:
- Local scope: Variables declared inside a method or block have a local scope and can only be accessed within that method or block. Once the method or block is exited, the variable is destroyed and its value is lost.
Example:
csharpvoid MethodA()
{
int x = 10;
Console.WriteLine(x); // outputs 10
}
Console.WriteLine(x); // Error: x is not defined
- Global scope: Variables declared outside any method or block have a global scope and can be accessed from anywhere in the code.
Example:
csharpint y = 20;
void MethodB()
{
Console.WriteLine(y); // outputs 20
}
Console.WriteLine(y); // outputs 20
It's also possible to have variables with the same name but with different scopes, as long as they are in different blocks or methods. In this case, the most local scope will take precedence over a wider scope.
How to use int in c#
In C#, int
is a data type that represents a 32-bit signed integer. You can use an int
variable to store whole numbers (integers) within a certain range, e.g.:
pythonint num = 42;
You can perform various operations on int
values, such as arithmetic operations (e.g. addition, subtraction, multiplication, division) and comparison operations (e.g. equality, less than, greater than).
For example:
C#int num1 = 10;
int num2 = 20;
int result = num1 + num2;
Console.WriteLine(result); // Output: 30
How to use double in c#
In C#, double
is a data type that represents a 64-bit floating-point number. You can use a double
variable to store decimal numbers with a high degree of precision, e.g.:
C#double d = 3.14;
You can perform various operations on double
values, such as arithmetic operations (e.g. addition, subtraction, multiplication, division) and comparison operations (e.g. equality, less than, greater than).
For example:
scssdouble d1 = 1.23;
double d2 = 4.56;
double result = d1 + d2;
Console.WriteLine(result); // Output: 5.79
Note that you can use the f
or F
suffix to specify a float
literal in C#, which is a single-precision floating-point number that occupies less memory than a double
.
How to use char in c#
In C#, char
is a data type that represents a single Unicode character, e.g.:
C#char c = 'A';
You can use a char
variable to store a single character or symbol, such as a letter, digit, punctuation mark, or whitespace. A char
value must be enclosed in single quotes ('
).
For example:
javachar ch = 'x';
Console.WriteLine(ch); // Output: x
You can perform various operations on char
values, such as comparing two characters for equality or ordering them in a certain way. You can also convert a char
value to its corresponding numeric representation (its Unicode code point) using the (int)
cast operator.
For example:
char ch1 = 'A';
char ch2 = 'B';
bool result = ch1 < ch2;
Console.WriteLine(result); // Output: True
How to use string in c#
In C#, string
is a data type that represents a sequence of Unicode characters. You can use a string
variable to store one or more characters, such as a word, sentence, or paragraph, e.g.:
string s = "Hello, World!";
A string
value must be enclosed in double quotes ("
). You can concatenate two or more strings using the +
operator, or use string interpolation to embed expressions within a string.
For example:
string name = "John";
string greeting = "Hello, " + name + "!";
Console.WriteLine(greeting); // Output: Hello, John!
csharpstring name = "John";
int age = 30;
string info = $"Name: {name}, Age: {age}";
Console.WriteLine(info); // Output: Name: John, Age: 30
You can also perform various operations on string
values, such as finding the length of a string, extracting a substring, or comparing two strings for equality or ordering.
For example:
javastring s1 = "Hello";
string s2 = "World";
bool result = s1 == s2;
Console.WriteLine(result); // Output: False
How to use bool in c#
In C#, bool
is a data type that represents a Boolean value, which can be either true
or false
. You can use a bool
variable to store a binary decision, such as a test for equality or a condition for a control flow statement, e.g.:
C#bool b = true;
You can perform various operations on bool
values, such as negating a value using the !
operator or combining two values using the logical &&
(and) or ||
(or) operators.
For example:
bool condition1 = 5 > 3;
bool condition2 = 2 < 1;
bool result = condition1 && condition2;
Console.WriteLine(result); // Output: False
bool condition1 = 5 > 3;
bool condition2 = 2 < 1;
bool result = condition1 || condition2;
Console.WriteLine(result); // Output: True