Here are some basic variable types in C++:

1. Integer Types:

   • short: 2 bytes, min: -32768, max: 32767

short s = 10;

1. • int: 4 bytes, min: -2147483648, max: 2147483647

int i = 20;

1. • long: 4 bytes (usually), min: -2147483648, max: 2147483647

long l = 30L; // 'L' suffix is optional but recommended for clarity.

1. • long long: 8 bytes, min: -9223372036854775808, max: 9223372036854775807

long long ll = 40LL; // 'LL' suffix is optional but recommended for clarity.

1. • Unsigned Integer Types:
     Each of the above types has an unsigned counterpart (e.g., unsigned int, unsigned long long) with twice the range.

2. Floating-Point Types:

   • float: 4 bytes, decimal fraction

float f = 3.14f; // 'f' suffix is optional but recommended for clarity.

2. • double: 8 bytes, higher precision than float

double d = 3.14;

2. • long double: 10 or more bytes, highest precision

3. Character Types:

   • char: 1 byte, stores a single character or ASCII value

char c = 'A';

3. • wchar_t: 2 or 4 bytes (depending on the platform), stores wide characters (e.g., Unicode)

4. Boolean Type:

   • bool: 1 byte, can have values true or false

bool b = true;

5. Pointer Types:

   • • Pointers store memory addresses and are used to manipulate the data at those addresses.

int* ptr; // pointer to an integer

Here’s an example that demonstrates some basic variable declarations and initialization:

#include <iostream>

int main() {

    int i = 10; // integer declaration and assignment

    double d = 3.14; // floating-point number declaration and assignment

    std::cout << "i = " << i << ", d = " << d << std::endl;

    bool b = true;

    char c = 'A';

    char s[20] = "Hello, World!";

    std::cout << "b = " << (b ? "true" : "false") << ", c = " << c << ", s = " << s << std::endl;

    return 0;

}

This will output:

i = 10, d = 3.14

b = true, c = A, s = Hello, World!

Overflow

Overflow is the situation where you try to store a number that exceeds the maximum range for the data type. When you try to store too large of a positive or negative number, the binary representation of the number is corrupted and you get a meaningless or erroneous result.

Underflow

Underflow is the situation where you try to store a number that exceeds the minimum range for the data type. When you try to store too small of a positive or negative number, the binary representation of the number is corrupted and you get a meaningless or erroneous result.

Note the operation (a / b) in our program. The / operator is the division operator.

As we can see from the example, if an integer is divided by another integer, we will get the quotient. However, if either divisor or dividend is a floating-point number, we will get the result in decimals.

In C++,

7/2 is 3

7.0 / 2 is 3.5

7 / 2.0 is 3.5

7.0 / 2.0 is 3.5

Example:

#include <iostream>

using namespace std;

int main() {

   int x;            // Declare an integer variable

   x = 20;          // Assign the value 20 to x

   cout << "The value of x is: " << x << endl; // Output: The value of x is: 20

   int a = 10;

   a += 5;   // Now a is 15

   cout << "After addition, a = " << a << endl;

   // Output: After addition, a = 15

   a -= 3;   // Now a is 12

   cout << "After subtraction, a = " << a << endl;

   // Output: After subtraction, a = 12

   a *= 2;   // Now a is 24

   cout << "After multiplication, a = " << a << endl;

   // Output: After multiplication, a = 24

   a /= 4;   // Now a is 6

   cout << "After division, a = " << a << endl;

   // Output: After division, a = 6

   return 0;

}

Example:

#include <iostream>

using namespace std;

int main() {

   int a = 10;

   int b = 20;

   cout << "a == b: " << (a == b) << endl; // Output: 0 (false)

   cout << "a != b: " << (a != b) << endl; // Output: 1 (true)

   cout << "a > b: " << (a > b) << endl;   // Output: 0 (false)

   cout << "a < b: " << (a < b) << endl;   // Output: 1 (true)

   cout << "a >= b: " << (a >= b) << endl; // Output: 0 (false)

   cout << "a <= b: " << (a <= b) << endl; // Output: 1 (true)

   return 0;

}

Example:

#include <iostream>

using namespace std;

int main() {

   //Logical AND

   int age = 25;

   bool isStudent = true;

   if (age > 18 && isStudent) {

       cout << "You are eligible for a student discount." << endl;

   } else {

       cout << "You are not eligible for a student discount." << endl;

   }

   //Logical OR

   int num = 7;

   if (num <= 0 || num >= 10) {

       cout << "The number is outside the range of 0 to 10." << endl;

   } else {

       cout << "The number is between 0 to 10." << endl;

   }

   //Logical NOT

   bool condition = false;

   if (!condition) { // Negates the condition

       cout << "Condition is false." << endl;

   } else {

       cout << "Condition is true." << endl;

   }

   return 0;

}

Example:

#include <iostream>

using namespace std;

int main() {

   int a = 7; // Binary: 0111

   int b = 5; // Binary: 0101

   cout << "Bitwise Operators Example:\n";

   cout << "a & b = " << (a & b) << "  // Bitwise AND\n";   // Result: 5 (0101)

   cout << "a | b = " << (a | b) << "  // Bitwise OR\n";    // Result: 7 (0111)

   cout << "a ^ b = " << (a ^ b) << "  // Bitwise XOR\n";   // Result: 2 (0010)

   cout << "~a = " << (~a) << "        // Bitwise NOT\n";   // Result: -8 (inverts bits)

   cout << "a << 1 = " << (a << 1) << "  // Left Shift\n";  // Result: 14 (1110)

   cout << "a >> 1 = " << (a >> 1) << "  // Right Shift\n"; // Result: 3 (0011)

   return 0;

}