C Language Overview

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Questions and Answers

What character precedes hexadecimal integers?

Both B and C (correct)

Which of the following is an invalid real number?

2.5e+05

321.55F

78688L

1.5E+0.5 (correct)

Which of the following is a valid integer constant?

0X2

037 (correct)

-ABCD

What is the correct representation for a double-precision floating-point constant?

78688L Signup and view all the answers

Which of the following is a character constant?

'A' Signup and view all the answers

Which of the following constants is not a valid string constant?

'World' Signup and view all the answers

In floating-point notation, what does the mantissa represent?

Either a real number or an integer expressed in decimal notation Signup and view all the answers

What is a common characteristic of hexadecimal integers?

They can use letters A-F as part of their representation. Signup and view all the answers

What is the result of the expression $10 + 3$?

13 Signup and view all the answers

Which arithmetic operator is used for division of two integers?

/ Signup and view all the answers

What is the output of the operation $10 % 3$?

1 Signup and view all the answers

What does the relational operator '!=' signify?

Not equal to Signup and view all the answers

If $x = 4.5$, what is the result of the expression $x >= 10$?

false Signup and view all the answers

In logical operations, what does '&&' represent?

Logical AND Signup and view all the answers

Which of the following expressions is true if $A$ is true and $B$ is false?

A || B Signup and view all the answers

What does the logical operator '!' do?

Inverts the truth value Signup and view all the answers

What is the result of using the prefix ++ operator in an expression?

The variable is incremented first, and then the expression is evaluated. Signup and view all the answers

What does the conditional operator (?:) evaluate first?

The first expression. Signup and view all the answers

Which of the following accurately describes the purpose of bitwise operators?

To manipulate or test data at the bit level. Signup and view all the answers

What does the sizeof operator return when applied to a variable?

The number of bytes occupied by the variable. Signup and view all the answers

Regarding the comma operator, which statement is true?

It connects related expressions evaluated left to right. Signup and view all the answers

Which bitwise operator is used to shift bits to the right?

Shift right (>) Signup and view all the answers

In a conditional operator expression, if the first expression evaluates to true, which of the following occurs?

The second expression is executed. Signup and view all the answers

Which of the following statements about prefix increment and decrement operators is correct?

Their precedence is the same as unary + and -. Signup and view all the answers

Which of the following is a valid symbolic constant definition?

#define MAX 100 Signup and view all the answers

What character represents a backslash escape sequence in output functions?

\ Signup and view all the answers

Which rule correctly describes the naming of a variable?

Variable names must start with a letter or underscore. Signup and view all the answers

Which of the following is an invalid variable name?

1stValue Signup and view all the answers

In the context of symbolic constants, which statement is true?

Symbolic names should not include spaces. Signup and view all the answers

How many characters can a variable name have at most according to ANSI rules?

31 Signup and view all the answers

What distinguishes different data types?

How much space they occupy in memory. Signup and view all the answers

Which of the following is a characteristic of symbolic constants?

A new definition cannot overwrite an existing symbolic constant. Signup and view all the answers

What type of variable is declared outside of any function in a C program?

Global variable Signup and view all the answers

Which of the following statements about local variables is true?

Local variables exist only while their block of code is executing. Signup and view all the answers

What happens to a local variable once the function that declares it finishes executing?

It gets deleted and can no longer be used. Signup and view all the answers

Which storage class specifier allows a variable to retain its value between function calls?

static Signup and view all the answers

What is the difference between the assignment of variables in C, such as 'a = b = 1'?

It is a shorthand way of assigning the same value to multiple variables. Signup and view all the answers

Which of the following is NOT a storage class in C?

dynamic Signup and view all the answers

How are global variables defined in a C program?

Outside of any function. Signup and view all the answers

What does the 'register' storage class indicate in a variable declaration?

The variable will be stored in a CPU register for faster access. Signup and view all the answers

What does the assignment operator 'a += 1' accomplish?

It adds 1 to the current value of 'a'. Signup and view all the answers

Which of the following statements correctly describes the role of prefix increment operators?

They increase the value of the operand before the assignment. Signup and view all the answers

What is the equivalent assignment of 'a %= b'?

a = a % b Signup and view all the answers

In the context of increment and decrement operators, what result does 'y = m++' yield when m is initially 5?

y = 5 and m = 6 Signup and view all the answers

Which statement about the advantages of assignment operators is true?

They help avoid repetition of variable names. Signup and view all the answers

What does the expression 'y = --m' produce when m starts at 5?

y = 5 and m = 4 Signup and view all the answers

Which of the following correctly depicts a result of the assignment 'a *= n + 1'?

a is assigned the product of a and (n plus 1). Signup and view all the answers

What is the initial value of 'm' after executing 'm = 5;' and then 'y = ++m'?

6 Signup and view all the answers

Study Notes

Unit I, Chapter I: Overview of C

C Language is a structured, high-level, machine-independent language.
ALGOL is the root of modern programming languages. Introduced in the 1960s.
ALGOL uses structured programming.
Corrado Bohm, Guiseppe Jacopini, and Edsger Dijkstra popularized structured programming concepts.
In 1967, Martin Richards created BCPL (Basic Combined Programming Language).
BCPL was primarily developed for system software.
In 1970, Ken Thompson created a new language called B.
B was created for UNIX operating systems at Bell Laboratories.
BCPL and B were typeless languages.
C was developed by Dennis Ritchie in 1972 at Bell Laboratories.
C was evolved from ALGOL, BCPL, and B, adding features like data types.
C was developed alongside the UNIX operating system.
ANSI (American National Standards Institute) appointed a technical committee to standardize C in 1983.
In December 1989, the committee approved a version of C, now known as ANSI C.
ISO (International Organization for Standardization) approved C in 1990, and this version is referred to as C89.
C99 is another important version.

Unit I, Chapter 1.2: Importance of C

C is a robust language with built-in functions and operators for complex programs.
C combines the capabilities of assembly language with high-level language features.
C is well-suited for writing system software and business packages.
Programs written in C are efficient and fast.
C is highly portable.
C is well-suited for structured programming.
C has the ability to extend itself.
A C program is a collection of functions supported by the C library.

Unit I, Chapter 1.3: Sample Program 1

Sample C code to print "Hello Program" to the console.
Includes function main(), curly braces {}, and comments.
Function main() is the entry point of a C program.

Unit I Chapter 1.4: Basic Structure of C Program

Documentation Section: (Optional) Comments about the program, author, etc.
Link Section: (Optional) Instructions for the compiler to link external functions.
Definition Section: (Optional) Symbolic constants are defined here.
Global Declaration Section: (Optional) Global variables and user-defined functions are declared here.
**main() Function:**The main function section starts with main() followed by {} brackets.
Declaration Part: Declares variables (data types).
Executable Part: Contains statements that execute the program logic.
Subprogram Section: (Optional) User-defined functions are placed here after the main function.

Unit I Chapter 1.5: Process of Compiling and Running a C Program

Creating the program.
Compiling the program.
Linking the program with functions from the C library.
Executing the program.

Unit I Chapter 1.6: Writing and Executing a C Program in UNIX

Writing the C program using text editors (e.g., vi, ed).
Entering the program into a file with a .c extension (e.g., firstcpgm.c).
Compiling the program (using cc or gcc). Using command cc filename.
Executing the compiled program (e.g., using a.out).

Unit I Chapter 1.7: Compiling and Linking

Use gcc or cc compilers to create executables.
Compile with command cc filename1, filename2, filename3...
Common command-line options: -lm (math library), -c (compiles without linking), -o filename (specifies output file name).

Unit II, Chapter 2.1: Character Set

Characters available for forming words, numbers, and expressions in C.
- Uppercase letters (A-Z), Lowercase letters (a-z).
- Digits (0-9).
- Special characters (e.g., comma, semicolon, parentheses, operators).
- White spaces (e.g., space, tab).

Unit II Chapter 2.2: C Tokens

Individual words and punctuation marks.
The smallest units in a C program are called tokens.
Examples: keywords, identifiers, constants, strings, operators, special symbols.

Unit II Chapter 2.2.1: Keywords and Identifiers

Keywords have fixed meanings that cannot be changed.
Keywords are used as building blocks for program statements.
Reserved words for specific tasks. Predefined and written in lowercase. Cannot be used as variable names.

Unit II Chapter 2.2.2: ANSI C Keywords

A list of predefined keywords in ANSI C. e.g., auto, break, case, char, const, continue, default, do, else, enum, extern, float, for, goto, if, int, long, register, return, short, signed, sizeof, static, struct, switch, typedef, union, unsigned, void, volatile, while.

Unit II Chapter 2.2.3: Identifiers

User-defined words that name entities (variables, arrays, functions, etc. ).
Rules for forming identifiers:
- Must start with a letter or underscore.
- Can include letters, digits, and underscores.
- First 31 characters are significant.
- Cannot use keywords.
- Case Sensitive.
- Cannot contain spaces.

Unit II Chapter 2.2.4: Constants

Fixed values that don't change during program execution.
Types of constants:
- Numeric (integer, real, etc.).
- Character.
- String.

Unit II Chapter 2.2.5: Integer Constant

Sequence of digits.
Types: decimal, octal, hexadecimal (e.g., 123, 017, 0xAF)

Unit II Chapter 2.2.6: Real Constants

Decimal values with optional decimal points (e.g., 3.14, -2.7, 1E-3). Can also be exponential.

Unit II Chapter 2.2.7: Character Constants

Single character enclosed in single quotes (e.g., 'A', '5', ' ').

Unit II Chapter 2.2.8: String Constants

Sequence of characters enclosed in double quotes (e.g., "Hello", "123", " ").

Unit II Chapter 2.2.9: Backslash Character Constants

For special characters in strings (e.g., '\n' for newline, '\t' for tab).

Unit II Chapter 2.2.10: Symbolic Constants

Named constants defined using #define. - Naming rules similar to identifiers. - Use for substituting values for better code readability.
Example: #define PI 3.14159.

Unit II Chapter 2.3: Variables

Data names that store values that can change during program execution.
Rules similar to identifiers.
Variables must have a data type.
Declaration: data_type variable_name;

Unit II Chapter 2.4: Declaration of Variables

Tell the compiler variable name and type.
Separate multiple variables with commas
Statements end with semicolons. e.g., int count; float total;

Unit II Chapter 2.5: Declaration Of Storage Class

Storage classes provide information about variables.
Types: auto, register, static, extern.
- Auto: Declared inside a block, Local (function), no default value
- Register: Stored in register, speed up execution, Limited data size & type.
- Static: Outside function scope. value persists.
- Extern: Declared outside any function but in the source code

Unit II Chapter 2.6: Assigning Values to Variables

Assigning values to variables with =. - Use = to give values to variables. - Example: x = 10;

Unit II Chapter 2.7: User defined types - `typedef`

Allow you to create new names for existing types. - e.g typedef int units; means from now on units can be used in place of int - Using this typedef will improve the readability and maintainability of the code.

Unit II Chapter 2.9: Enumerated Types

Allows you to create a named set of constant values.
- Example: enum color {RED, GREEN, BLUE};

Unit III, Chapter 3.1: Introduction to Operators and Expressions

Symbols performing operations on operands.
There are various categories of operators. e.g Arithmetic, relational, logical, assignment, increment/decrement, conditional, bitwise, special.
Expressions: Combinations of operators, operands, and constants combined according to language syntax

Unit III Chapter 3.1.1: Arithmetic Operators

Operations for numerical calculations (e.g., +, -, *, /, %)

Unit III Chapter 3.1.2: Relational Operators

Used to compare values (e.g., == for equal, != for not equal, < for less than).

Unit III Chapter 3.1.3: Logical Operators

Operators for logical operations (e.g., && for AND, || for OR, ! for NOT).

Unit III Chapter 3.1.4: Assignment Operators

Used to assign values to variables (e.g., =, +=, -=, *=, /=, %=).

Unit III Chapter 3.1.5: Increment and Decrement Operators

Used to increment or decrement variables by one (e.g., ++, --).

Unit III Chapter 3.1.6: Conditional Operator

Ternary operator for conditional expressions (e.g., exp1? exp2: exp3).

Unit III Chapter 3.1.7: Bitwise Operators

Used to manipulate bits of data at a low level. (e.g., &, |, ^, <<, >>)

Unit III Chapter 3.1.8: Special Operators

Operators that perform specific tasks (e.g., sizeof, comma operator).

Unit III Chapter 3.2: Arithmetic Expressions

Combining constants, variables, and operators for numerical calculations.
Evaluation in accordance with precedence and associativity rules.

Unit III Chapter 3.3: Operator Precedence and Associativity

Rules determining the order of operations.
Order of operation for operators.
Parentheses have highest priority.

Unit III Chapter 3.4: Type Conversion

Implicit (automatic) and explicit (static) type conversion.
Conversion hierarchy.

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Description

This quiz covers the foundational concepts of the C programming language, including its history and evolution from earlier languages like ALGOL, BCPL, and B. It highlights key figures in structured programming and the significance of ANSI standardization. Test your understanding of how C was developed and its role alongside UNIX.