Expression In C++

An expression is a combination of operators, constants and variables. An expression may consist of one or more operands, and zero or more operators to produce a value.

Types Of Expressions

• Constant expressions

  Constant Expressions consists of only constant values. A constant value is one that doesn't change. It is an expression whose value is determined at the compile-time. It can be composed of integer, character, floating-point, and enumeration constants.

  Example:-

  #include <iostream>
  using namespace std;
  
  int main() {
    int a; // variable declaration.
    a = (6 / 3) + 2; // constant expression
    cout << "The value of a is: " << a; // displaying the value of a.
    return 0;
  }

  Output:-

  The value of a is: 4

• Integral expressions

  Integral Expressions are those which produce integer results after implementing all the automatic and explicit type conversions.

  Example:-

  #include <iostream>
  using namespace std;
  
  int main() {
    int a = 7, b = 5, c = 9, d; // variable declaration.
    d = a + b + c;
    cout << "The value of d is: " << d; // displaying the value of a.
    return 0;
  }

  Output:-

  The value of d is: 21

• Float expressions

  Float Expressions are which produce floating point results after implementing all the automatic and explicit type conversions.

  Example:-

  #include <iostream>
  using namespace std;
  
  int main() {
    float a = 7.5, b = 5.5, c = 9.5, d; // variable declaration.
    d = a + b + c;
    cout << "The value of d is: " << d; // displaying the value of d.
    return 0;
  }

  Output:-

  The value of d is: 22.5

• Pointer expressions

  This particular pointer expression in C++ produces an address value as an output of the program.

  Example:-

  #include <iostream>
  using namespace std;
  
  int main() {
    int X[] = {1, 2, 3, 4, 5}; // array initialization
    int *ptr; // pointer declaration
    ptr = X; // assigning the base address of the array to the pointer ptr
    ptr = ptr + 1; // incrementing the value of the pointer
  
    cout << "Value of the second element of an array: " << *ptr << endl;
    return 0;
  }

  Output:-

  Value of the second element of an array: 2

• Relational expressions

  A relational expression is an expression that produces a value of type bool, which can be either true or false. It is also known as a boolean expression. When arithmetic expressions are used on both sides of the relational operator, arithmetic expressions are evaluated first, and then their results are compared.

  Example:-

  #include <iostream>
  using namespace std;
  
  int main() {
    int x = 7, y = 4; // variable declaration.
    bool d = x > y; // relational expression
    cout << "The value of d is: " << d; // displaying the value of d.
    return 0;
  }

  Output:-

  The value of d is: 1

• Logical expressions

  Logical Expressions combine two or more relational expressions and produces bool type results.

  Example:-

  #include <iostream>
  using namespace std;
  
  int main() {
    int x = 7, y = 4, z = 5; // variable declaration.
    bool d = (x > y); // relational expression
    cout << ((x > y) || (x > z));
    return 0;
  }

  Output:-

  1

• Bitwise expressions

  Bitwise Expressions are used to manipulate data at bit level. They are basically used for testing or shifting bits.

  Example:-

  #include <iostream>
  using namespace std;
  
  int main() {
    int x = 7; // variable declaration.
    cout << (x >> 1) << endl;
    return 0;
  }

  Output:-

  3

• Special assignment expressions

  Special assignments in C++ can be classified depending on the value of the variable that is assigned

  • Chained assignment expressions - In chained assignment expression assigns the same values more than once by using only one statement

    Example:-

    #include <iostream>
    using namespace std;
    
    int main()
    {
      int x; // variable declaration
      int y; // variable declaration
      x = y = 80; // chained assignment
      cout << "Values of 'x' and 'y' are: " << x << "," << y << endl;
      return 0;
    }

    Output:-

    Values of 'x' and 'y' are : 80,80

  • Embedded assignment expressions - In this embedded assignment expression one expression is enclosed within another assignment expressions

    Example:-

    #include <iostream>
    using namespace std;
    
    int main()
    {
      int x; // variable declaration
      int y; // variable declaration
      x = 10 + (y = 90); // embedded assignment expression
      cout << "Value of 'x' is " << x << endl;
      return 0;
    }

    Output:-

    Value of 'x' is 100

  • Compound Assignment - A compound assignment expression is an expression which is a combination of an assignment operator and bioy operator.

    Example:-

    #include <iostream>
    using namespace std;
    
    int main()
    {
      int x = 5; // variable declaration
      x+= 10;    //Here (+=) is compound assignment operator
      cout << "Value of 'x' is " << x << endl;
      return 0;
    }

    Output:-

    Value of 'x' is 15