JNTU MCA 2018 COMPUTER PROGRAMMING Previous Question Paper (January - 2018 - R13)

Operator precedence determines the order in which different operators are evaluated in an expression containing multiple types of operators. Operators with higher precedence are evaluated before those with lower precedence. For example, in the expression 5 + 3 * 2, the multiplication operator (*) has higher precedence than addition (+), so it is evaluated first, resulting in 11.

Operator associativity defines the direction of evaluation (left-to-right or right-to-left) when an expression contains multiple operators of the same precedence level. Most operators, such as addition, subtraction, multiplication, and division, are left-associative, meaning they are evaluated from left to right. Assignment operators and unary operators are typically right-associative, meaning they are evaluated from right to left.

Understanding these rules is essential for predicting the outcome of complex expressions and ensuring that code executes as intended by the programmer.

Preprocessor commands, often called directives, are instructions to the C preprocessor that are executed before the actual compilation of the source code begins. These commands always start with a hash symbol (#) and are not terminated by a semicolon.

Common preprocessor directives include:

• Macro Substitution (#define): Used to define constants or macros to replace specific tokens in the source code.
• File Inclusion (#include): Used to insert the contents of another file, such as header files, into the current source file.
• Conditional Compilation (#if, #ifdef, #ifndef, #else, #elif, #endif): Allows the compiler to selectively compile specific sections of code based on defined conditions.
• Pragma Directives (#pragma): Provides additional information to the compiler, such as specific optimization settings or memory alignment, which are implementation-defined.
• Error and Line Control (#error, #line): Used to generate custom error messages during compilation or to reset line numbering for debugging purposes.