C Programming Tokens and Characters

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Questions and Answers

What is a token in a C program?

A special character used for formatting

The smallest unit in a C program that can have a specific meaning (correct)

A keyword that defines a variable

A data type that can be modified

Which of the following statements about C keywords is TRUE?

C has a total of 32 keywords written in small letters (correct)

Keywords can be used as identifiers

Keywords are always written in capital letters

Keywords can be changed to suit user preferences

Which rule for creating identifiers is correct?

Identifiers can start with numbers

Identifiers can use underscores instead of spaces (correct)

Identifiers can be the same as keywords if capitalized

Identifiers can have spaces between words

Which of the following is an invalid identifier in C?

2ndVariable Signup and view all the answers

What will happen if you use a keyword as an identifier?

An error will occur during compilation Signup and view all the answers

Which of the following is not allowed in identifiers?

Special symbols Signup and view all the answers

What is the maximum number of characters considered in a word limit for identifiers?

31 characters Signup and view all the answers

Which statement correctly differentiates keywords from identifiers?

Identifiers are user-defined names. Signup and view all the answers

What is the memory requirement of data types mainly used for?

To indicate the type of data to be stored. Signup and view all the answers

What is the bit representation of a single byte?

8 bits Signup and view all the answers

What is the memory size occupied by a double data type?

8 bytes Signup and view all the answers

What is the range of values for an unsigned char data type?

0 to 255 Signup and view all the answers

Which of the following qualifiers can be used with the int data type?

All of the above Signup and view all the answers

What is the size of a short int in memory on most machines?

2 bytes Signup and view all the answers

How many bytes does a long double typically occupy?

10 to 16 bytes Signup and view all the answers

Which of the following is NOT a rule for declaring variables in C?

Variable names can start with a digit Signup and view all the answers

What does variable declaration do in C?

Specifies the type and name of the variable Signup and view all the answers

Which of these data types can hold both positive and negative values?

float Signup and view all the answers

What is the correct way to declare multiple variables of type int?

int x, y, z; Signup and view all the answers

Which modifier is not applicable to char data types?

short Signup and view all the answers

What section of a C program contains user-defined functions that can be called from the main function?

Subprogram Section Signup and view all the answers

What keyword must begin the execution of any C program?

main Signup and view all the answers

Which section of a C program is used to declare global variables that can be accessed throughout the program?

Global Declaration Section Signup and view all the answers

What type of statement begins with the symbol '#' in a C program?

Preprocessor directive Signup and view all the answers

Which part of the main function contains statements that will be executed?

Executable Part Signup and view all the answers

Which of the following is NOT a section in a typical C program?

Namespace Section Signup and view all the answers

In the context of the provided content, what is the purpose of the 'sqrt' function shown in the example?

To calculate the square root Signup and view all the answers

What would be the result of executing printf("%d", a); if a is declared globally with a value of 10?

10 Signup and view all the answers

Which of the following is a valid octal integer constant?

057 Signup and view all the answers

What is the correct representation for a hexadecimal integer constant?

0X5 Signup and view all the answers

Which of the following is not a rule for writing a real constant in fractional form?

Can contain blank spaces Signup and view all the answers

Identify the invalid character constant from the following options.

'' Signup and view all the answers

Which of the following represents a valid exponential form real constant?

3.5e4 Signup and view all the answers

What is a symbolic constant in C programming?

A feature that allows preprocessor directives Signup and view all the answers

Which of the following expressions represents a valid character constant?

'9' Signup and view all the answers

Which mathematical operator is used in C programming for logical AND?

&& Signup and view all the answers

Study Notes

White Space Characters

Tab: '\t'
Newline: '\n'

Character Set

Represented by ASCII codes

C Tokens

The smallest building blocks of a C program
Include keywords, identifiers, constants, operators, and punctuation marks

Types of C Tokens

Keywords: Reserved words with fixed meanings
- Cannot be redefined by the user
- Examples: int, float, char, void
Identifiers: User-defined names for variables, arrays, functions, and other program elements
- Must follow specific rules:
  - Start with an alphabet or underscore
  - Digits can be used after the first character
  - Cannot contain spaces or special symbols
  - Cannot be keywords
  - Case sensitive
Constants: Fixed values that cannot be changed during program execution
- Examples: 10, 3.14159, 'A', "Hello"
Operators: Symbols that perform specific operations on data
- Examples: +, -, *, /, %, =, >, <
Punctuation Marks: Symbols used to separate or organize C code
- Examples: {, }, ;, ,

Datatypes

Define the type of data that a variable can hold
Determine the amount of memory allocated for a variable
Used in variable declarations

Classification of Datatypes

Primary Datatypes: Also called built-in or fundamental data types
- Examples: char, int, float, double
Derived Datatypes: Created using primary data types
- Examples: Arrays, structures, pointers, unions
User-defined Datatypes: Defined by programmers using keywords like enum, struct, and typedef

Primary Data Types

char: Stores single characters
- Encoded using the ASCII character set
- Occupies 1 byte of memory
int: Stores whole numbers (integers)
- Can be signed (positive, negative, and zero) or unsigned (only positive and zero)
- Occupies 2 or 4 bytes of memory depending on the system architecture
float: Stores single-precision floating-point (decimal) numbers
- Provides 4 bytes of memory for storage
double: Stores double-precision floating-point numbers
- Provides 8 bytes of memory for storage
- Often used for higher precision calculations

Qualifiers/Modifiers

Used to alter the size and sign of primary data types
Size: short, long
Sign: signed, unsigned

Variables

Named memory locations that can store values
Can be modified during program execution
Must be declared before use
Can be initialized during declaration
Memory Address: The location of the variable in memory.
Value: The data stored in the variable.
Name: The identifier used to access the variable.

Types of Variables

Local: Declared inside a function
- Scope is limited within the function
Global: Declared outside of all functions
- Scope is accessible throughout the program

Constants

Fixed values that cannot be changed during program execution
Useful for representing unchanging data, such as mathematical constants or configuration settings

Types of Constants

Integer Constants: Whole numbers
- Decimal: Base-10 numbers (e.g., 123)
- Octal: Base-8 numbers (e.g., 0177)
- Hexadecimal: Base-16 numbers (e.g., 0x4b)
Real Constants: Floating-point numbers (decimals)
- Fractional Form: e.g., 3.14159, -0.005
- Exponential Form: e.g., 1.23e4
Character Constants: Single characters enclosed in single quotes
- e.g., 'A', '5', '$'
String Constants: Sequences of characters enclosed in double quotes
- e.g., "Hello", "World", "123"

Operators

Symbols that perform mathematical, logical, or other operations on data

Symbolic Constants

Defined using the #define directive
Used to give meaningful names to constants
Can be used throughout the program

Program Structure

Link Section: Includes header files (e.g., stdio.h, math.h)
Definition Section: Defines constants using #define
Global Declaration Section: Declares global variables and functions
Global Function Section: Contains global functions
Main Function Section: The entry point for program execution
- Must have int main() {}
- Contains declaration and execution statements
User-Defined Function Section: Contains user-defined functions

Sections of a C program

#include <stdio.h>: Header file for standard input/output functions
#define PI 3.14: Symbolic constant declaration
int main(): The main function
// Welcome to C: Single-line comment
void myfunction(): A user-defined function
int a = 10, b = 20;: Global variable declaration

Execution

The program begins execution at the main() function.

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Description

Explore the foundational elements of C programming in this quiz, focusing on various types of C tokens including keywords, identifiers, constants, and operators. Test your understanding of character sets and whitespace characters integral to writing effective C code.