C Programming Concepts

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Questions and Answers

What is the maximum number of characters allowed in a variable name?

64 characters

8 characters

16 characters

30 characters (correct)

Which of the following is a valid variable name?

class mark

student_name (correct)

student-name

1stVariable

What should a variable name not be?

Descriptive enough

A reserved word (correct)

Numeric in nature

Less than 8 characters

What is the correct syntax for declaring multiple integer variables in C?

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

What symbol is used to assign a value to a variable in C?

= Signup and view all the answers

Which of the following types of constants is NOT recognized in C?

Symbolic constants Signup and view all the answers

In C, what type of variable retains its value even after the block in which it is declared has exited?

Static variable Signup and view all the answers

How many types of variables are identified in C programming?

Three Signup and view all the answers

Which of the following is a valid decimal constant?

-9 Signup and view all the answers

What is a requirement for octal constants in C programming?

Must be prefixed with 0. Signup and view all the answers

In C programming, which of the following is NOT a valid hexadecimal constant?

0x1G Signup and view all the answers

How must hexadecimal constants be prefixed?

0x or 0X Signup and view all the answers

Which of the following represents a valid floating point constant?

1.2e3 Signup and view all the answers

Which statement about integer constants in C programming is FALSE?

Decimal constants can have a leading zero. Signup and view all the answers

Identify the correct digits that can be used in octal constants.

0-7 only Signup and view all the answers

Floating point constants in C can be expressed in which of the following forms?

Fractional form. Signup and view all the answers

What is the main purpose of the increment operator?

To increment the current value of a variable by adding 1 Signup and view all the answers

Which statement about the increment operator is false?

It can be used with constant values. Signup and view all the answers

In the expression 'b = ++y', what value does 'b' take if 'y' is initially 5?

6 Signup and view all the answers

What does the post-increment operator do in the expression 'b = x++' when 'x' is 5?

Assigns 5 to 'b' Signup and view all the answers

Which of the following statements is true about pre-increment and post-increment operators?

Pre-increment increments the value before it's used in an expression. Signup and view all the answers

Why can't the increment operator be used on constant values?

Because constants cannot change. Signup and view all the answers

What will happen if you try to execute 'b = ++5' in code?

It will cause a compilation error. Signup and view all the answers

What is the result of the bitwise AND operation between the integers 12 and 25?

8 Signup and view all the answers

What symbol denotes the increment operator?

++ Signup and view all the answers

Which operator is used to perform a bitwise OR operation in C programming?

| Signup and view all the answers

What is the outcome of applying the bitwise XOR operator on 12 and 25?

21 Signup and view all the answers

When the bitwise complement operator ~ is applied to the number 35, what is the expected result in terms of two's complement?

-36 Signup and view all the answers

How is the 2's complement of a binary number derived?

By inverting all bits and adding 1. Signup and view all the answers

Which of the following best describes the condition for a bit to be 1 in a bitwise OR operation?

At least one bit must be 1. Signup and view all the answers

What is the correct binary representation of the number 29?

00011101 Signup and view all the answers

In C programming, what would be the output of the statement `printf("Output = %d", a | b);` when a is 12 and b is 25?

29 Signup and view all the answers

What is the maximum number of characters that a C identifier can have?

31 Signup and view all the answers

Which of the following is NOT a valid C identifier?

1stVar Signup and view all the answers

Which of the following keywords is correctly written?

float Signup and view all the answers

What type of data does 'float' represent in C?

Floating-point number Signup and view all the answers

Which of the following is an enumeration data type in C?

enum Signup and view all the answers

Which of the following data types cannot store negative values?

unsigned int Signup and view all the answers

How many bytes does the 'double' data type occupy in C?

8 Signup and view all the answers

What does a variable represent in C programming?

A name for a memory location Signup and view all the answers

Which of the following represent basic data types in C?

int, float, char, double Signup and view all the answers

What is the range of a 'signed short' in C?

-128 to 127 Signup and view all the answers

Which of these is counted as a derived data type?

pointer Signup and view all the answers

What is a characteristic of keywords in C programming?

They have fixed meanings that cannot be changed. Signup and view all the answers

What is the maximum value of an 'unsigned int' in C?

4294967295 Signup and view all the answers

Study Notes

C Identifier Rules

C compiler only recognizes the first 31 characters of an identifier.
Identifiers can include alphabets and numbers, but must start with an alphabet.
Identifiers can use the underscore symbol (_) but not other special characters or spaces.
Identifiers cannot be reserved keywords.

Keywords

Keywords are reserved words with predefined meanings.
Keywords cannot be used as variable names, constant names, etc.
All keywords are written in lowercase.
C has 32 keywords: auto, break, case, char, const, continue, default, do, double, enum, else, extern, float, for, goto, if, int, long, register, return, signed, short, static, sizeof, struct, switch, typedef, union, unsigned, void, volatile, while.

Data Types

Data types are used to allocate memory for data and specify what type of data a variable can store.
Four main data types in C:
- Basic Data Type: int, char, float, double
- Derived Data Type: array, pointer, structure, union
- Enumeration Data Type: enum
- Void Data Type: void

Basic Data Types

Basic data types are either integer-based or floating-point based.
Memory size of basic data types may vary depending on 32-bit or 64-bit operating systems.
Size and ranges of data types with type qualifiers:

Type	Size (bytes)	Range	Control String
`char` or `signed char`	1	-128 to 127	`%c`
`unsigned char`	1	0 to 255	`%c`
`int` or `signed int`	2	-32768 to 32767	`%d` or `%i`
`unsigned int`	2	0 to 65535	`%u`
`short int` or `signed short int`	1	-128 to 127	`%d` or `%i`
`unsigned short int`	1	0 to 255	`%d` or `%i`
`long int` or `signed long int`	4	-2147483648 to 2147483647	`%ld`
`unsigned long int`	4	0 to 4294967295	`%lu`
`float`	4	3.4E-38 to 3.4E+38	`%f` or `%g`
`double`	8	1.7E-308 to 1.7E+308	`%lf`
`long double`	10	3.4E-4932 to 1.1E+4932	`%Lf`

Variables

A variable is a name that refers to a memory location used to store data.
Variables are changeable and their values can be modified during program execution.

Variable Declaration

Variables must be declared before they are used in a program.
Syntax: data_type variable-1, variable-2, ..., variable-n;
Separated by commas and the declaration ends with a semicolon.
Example: int x, y, z; float a, b; char m, n;

Assigning Values to Variables

Values can be assigned to variables using the assignment operator (=).
Syntax: variable = constant;
Example: x = 100; a = 12.25; m = 'f';
Values can also be assigned at the time of declaration: data_type variable = constant;

Types of Variables

Local Variable: Declared inside a function or block of code. Only accessible within that scope.
Global Variable: Declared outside of any function. Accessible from anywhere in the program.
Static Variable: Declared using the static keyword. Retains its value even after the function ends.

Constants

Constants refer to fixed values that don't change during program execution.
Also called literals.
Types of constants in C:
- Integer Constants:
  - decimal constant (base 10): 0, -9, 22, etc.
  - octal constant (base 8): starts with 0 (e.g., 021, 077, 033).
  - hexadecimal constant (base 16): starts with 0x (e.g., 0x7f, 0x2a, 0x521).
- Real or Floating Point Constants: have fractional or exponential forms (e.g., -2.0, 0.0000234, -0.22E-5).
- Character Constants: enclosed in single quotes (e.g., 'a', 'b', 'c').
- String Constants: enclosed in double quotes (e.g., "hello", "world").
- Backslash Character Constants: special characters represented with a backslash (e.g., '\n' for newline).

Increment Operators

Increment operators increase the value of a variable by 1.
Two types:
- Pre-Increment: Increments the variable's value before using it in the expression (++y).
- Post-Increment: Increments the variable's value after using it in the expression (x++).

Bitwise Operators

Work on individual bits of data.
Types:
- Bitwise AND (&): Results in 1 if both corresponding bits are 1.
- Bitwise OR (|): Results in 1 if at least one corresponding bit is 1.
- Bitwise XOR (^): Results in 1 if corresponding bits are different.
- Bitwise Complement (~): Inverts each bit (0 to 1, 1 to 0).

2's Complement

A method used to represent negative numbers in binary.
The 2's complement of a number is equal to its complement (inverting all bits) plus 1.

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Description

Test your knowledge of C programming rules including identifier naming conventions, keyword usage, and data types. This quiz covers the essentials you need to understand to write valid C code effectively.