C Programming - 1

SELECT CASE and both single-alternative and double-alternative block IF statements are all control structures that direct program flow. END is a termination keyword used to close blocks, but it doesn't control program flow itself. END simply marks the conclusion of a block structure like IF or SELECT CASE.

Supercomputers are the largest and most powerful computers designed for complex calculations. Mainframes are large-scale servers for enterprise applications. Minicomputers are mid-range systems smaller than mainframes. Microcomputers (personal computers) are the smallest. This hierarchy reflects both physical size and computational capacity, from largest to smallest.

Control statements like IF, SELECT CASE, and loops allow programmers to alter the sequential execution of a program. Inquiry-and-response handles user input, Print displays output, and Flowcharting is a design tool. Only control statements actively change the flow of program execution by making decisions or repeating actions based on conditions.

In block IF structures, the block must be properly terminated. The END IF statement marks the conclusion of the IF block. While END alone terminates other structures like SELECT CASE, the specific syntax for block IF requires END IF to properly close the conditional block and maintain code clarity.

Non-executable statements like REM (remark/comment) are ignored during program execution. When a non-executable statement appears after a block IF, the program simply skips it and continues to the next executable statement. The block IF has already been evaluated, and execution proceeds to the first executable instruction following the REM statement. No error occurs, and the IF is not re-executed.

A double-alternative block IF statement has both a THEN clause and an ELSE clause. This structure handles two possible outcomes - one for when the condition is true, and one for when it's false. Single-alternative IF statements only have a THEN clause, and SELECT CASE handles multiple alternatives through different CASE blocks.

A menu is a user interface element that displays a list of available program functions or options. Users select one item from the menu to invoke that specific function. Collating sequences determine character ordering, boolean operators combine logical conditions, and relational operators compare values - none of these display selectable function lists.

In a double-alternative block IF, the condition is evaluated once. If true, the THEN clause executes and the ELSE clause is skipped. If false, the ELSE clause executes and the THEN clause is skipped. Only one of the two clauses ever executes during a single pass through the IF statement - never both, and never neither.

Numeric constants in programming must contain only digits, a decimal point, and optional sign. Option A (14.85) is a valid decimal, Option B (98) is a valid integer, and Option C (– 1890) with negative sign is valid. Option D ($75) contains a currency symbol, making it invalid as a numeric constant - the dollar sign is not part of numeric representation in programming.

Block IF statements evaluate conditions using relational operators (like =, <, >, <=, >=) to compare values. These values can be constants (like 5 or "hello"), variables (like x or name$), or arithmetic expressions (like x + y or score * 2). The IF statement then branches based on whether the condition is true or false.

Character string constants must be enclosed in matching quotation marks. You can use either single quotes (') or double quotes ("), but you must use the same type at the beginning and end. Option B starts with a single quote and ends with a double quote, making it invalid.

Programming languages enforce type compatibility when comparing variables. You cannot directly compare a string variable (which stores text) to a numeric variable (which stores numbers) because they represent different kinds of data. This type mismatch will generate an error rather than attempting an invalid comparison.

The CLS (Clear Screen) command is used to clear the output screen in BASIC programming. This removes any previous text or output, providing a clean slate for displaying new program results. It's especially useful when you want fresh, uncluttered output for the user.

Numeric constants in programming cannot contain commas within the number. While we write numbers like 10,345.8 in everyday writing with commas as thousand separators, programming languages treat commas as syntax separators, not part of the number itself. The correct format would be 10345.8 without the comma.

You cannot use reserved keywords (special words that have built-in meaning in the language) as variable names. "PRINT" is a keyword that instructs the program to display output, so it cannot be used as a variable name to store values. This would create confusion for the compiler/interpreter about whether you mean the command or a variable.

Variable names in most programming languages must begin with a letter (a-z or A-Z). They cannot start with numbers or special characters. After the first letter, variable names can typically include numbers and sometimes underscores, but the first character must always be alphabetic.

In BASIC programming, string variables are indicated by a dollar sign ($) suffix. This distinguishes them from numeric variables. A valid string variable name consists of letters followed by $, with no spaces in the name. Address$ follows this pattern correctly, making it a valid string variable name.

Parentheses are used in programming (and mathematics) to override the default order of operations. Operations inside parentheses are performed first, before operations outside them. This allows programmers to control exactly how complex expressions are evaluated and ensure calculations happen in the intended sequence.

A literal (or literal constant) is a value that is written directly in code, rather than being stored in a variable. Literals can be numeric (like 42 or 3.14), string (like "hello"), or even consist of special characters. They represent fixed values and can include any combination of letters, numbers, and special characters depending on the data type.

In an IF-THEN-ELSE structure, when the condition evaluates to true, only the THEN clause is executed. The ELSE clause is skipped entirely.

The LET statement assigns the result of N1 + N2 + N3 to the variable Sum. This calculates the arithmetic sum of the three numbers.