JNTU B.Tech I Year COMPUTER PROGRAMMING IN C Previous Question Paper (October/November - 2020 - R16)

C-tokens are the smallest individual units of a C program that are meaningful to the compiler. The entire source code is parsed into these tokens during the compilation process. They are categorized into the following types:

• Keywords: Reserved words with fixed meanings, such as int, float, if, and while, which cannot be used as identifiers.
• Identifiers: Names given to variables, functions, arrays, or structures. They must start with a letter or underscore and contain only letters, digits, or underscores.
• Constants: Fixed values that do not change during program execution, including integer constants (e.g., 10), floating-point constants (e.g., 3.14), character constants (e.g., 'A'), and string literals (e.g., "Hello").
• Strings: A sequence of characters enclosed in double quotes, automatically terminated by a null character (\0).
• Operators: Symbols that perform arithmetic, logical, relational, or bitwise operations, such as +, -, *, /, ==, and &&.
• Special Symbols: Characters with specific syntactic roles, such as brackets [], parentheses (), braces {}, commas ,, and semicolons ;.

Operator precedence and associativity define the order in which expressions are evaluated when multiple operators are present.

Operator Precedence: This determines the priority of operators. When an expression contains different types of operators, the one with higher precedence is evaluated first. For example, in the expression 5 + 3 * 2, the multiplication operator (*) has higher precedence than addition (+), so it is performed first, resulting in 11 rather than 16.

Operator Associativity: This determines the direction of evaluation when operators in an expression have the same precedence. Associativity can be either left-to-right or right-to-left.

• Left-to-Right: Most binary operators, such as +, -, *, and /, follow this rule. For instance, 10 - 5 - 2 is evaluated as (10 - 5) - 2 = 3.
• Right-to-Left: Unary operators (like !, ++, --) and assignment operators (=, +=) follow this rule. For example, in the expression a = b = 5, the assignment is performed from right to left, assigning 5 to b, and then b to a.

Understanding these rules is essential for writing predictable code and avoiding logical errors in complex expressions.