Problem Solving Through C (BCA) 1st Sem Previous Year Solved Question Paper 2022

A constant is a value that doesn't change during the execution of a program. Constants are used to represent fixed values, such as numbers, characters, or strings, and they are essential for making programs more readable and maintainable. C language supports various types of constants, including:

Integer Constants:

• Integer constants are whole numbers without a decimal point.

• They can be represented in decimal (base 10), octal (base 8), or hexadecimal (base 16) format.

• Examples: 42, 0x2A (hexadecimal), 052 (octal).

Floating-Point Constants:

• Floating-point constants represent real numbers with a decimal point.

• They can be written in decimal notation with or without an exponent.

• Examples: 3.14, -0.001, 2.0e-3 (scientific notation).

Character Constants:

• Character constants are enclosed in single quotes (' ').

• They represent a single character or an escape sequence.

• Examples: 'A', '\n' (newline), '\t' (tab).

String Constants:

• String constants are enclosed in double quotes (" ").

• They represent sequences of characters.

• Example: "Hello, World!"

Enumeration Constants:

• Enumeration constants are user-defined constants created with the enum keyword.

• They provide a way to create symbolic names for integer values.

• Example:

 enum Day { SUN, MON, TUE, WED, THU, FRI, SAT };

Macro Constants:

• Macro constants are defined using the ‘#define’preprocessor directive.

• They are typically used for defining constants that are replaced with their values during preprocessing.

• Example:

#define PI 3.14159265359

Constant Pointers:

• Pointers that point to constant values or memory locations.

• They are declared using the ‘const’ keyword.

• Example:

const int* ptr; // Pointer to a constant integer.

1. Literal Constants:

   • Literal constants are used to represent special values like NULL or '\0' (null character).

   • NULL is often used to represent a null pointer.

   • '\0' is the string terminator in C.

2. Boolean Constants:

   • In C99 and later, _Bool is a data type used for representing Boolean values.

   • Constants 0 and 1 can be used to represent false and true.