C Programming Basics Quiz

Integers for Boolean Tests

• Integers are used for boolean tests in C:
  • 0 is equivalent to false
  • Any non-zero value is considered true

Variable Names in C

• C differentiates between uppercase and lowercase letters.
• Variable names are written in lowercase for clarity.
• Uppercase letters are used for symbolic constants defined by #define.
• Variable names must start with a letter and cannot contain spaces.
• Only an underscore is allowed as a special character.
• Reserved keywords like while, if, case, and function names cannot be used as variable names.

Variable Declarations in C

• To declare a variable, prefix its name with its data type.
• There are 6 basic data types in C:
  • char: Character, occupies one byte (8 bits), with a range of -128 to 127.
  • short: Integer, occupies two bytes, with a range of -32,768 to 32,767.
  • int: Integer, occupies four bytes, with a range of -2,147,483,648 to 2,147,483,647.
  • long: Integer, occupies 8 bytes, with a range of -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807.
  • float: Real number, occupies four bytes, with a range of approximately -10^38 to 10^38.
  • double: Real number, occupies eight bytes, with a range of approximately -10^308 to 10^308.
• Each type can be prefixed with unsigned, forcing the variable to hold only positive values.

Preprocessor Directives

• #include: Allows the use of functions like printf() and scanf().
• #include <math.h>: Allows the use of mathematical functions.
• #define PI 3.14159: Defines the constant PI.
• #undef PI: Undefines the constant PI from this point onwards.
• #ifdef PI: Compiles instructions 1 if PI is defined, otherwise compiles instructions 2.
• #else: Provides alternative instructions if PI is not defined.
• #endif: Ends the conditional compilation block.

General Structure of a C Program

• Only one preprocessor directive is mandatory: #include <stdio.h>.
• This directive enables functions like printf() for screen output and scanf() for keyboard input.

The main() Function in C

• The main() function is the starting point of every C program.
• It's defined using the syntax: main() { ... }.
• Instructions within the main() function are enclosed in curly braces and end with semicolons.
• All variables must be declared before they can be used within main().

Examples of Variable Declarations in C

• int a;: Declares an integer variable named a.
• int z = 4;: Declares an integer variable named z and initializes it with the value 4.
• unsigned int x;: Declares an unsigned integer variable named x.
• float zx, zy;: Declares two float variables named zx and zy.
• float zx = 15.15;: Declares a float variable named zx and initializes it with the value 15.15.
• double z;: Declares a double-precision real number variable named z.
• char zz;: Declares a character variable named zz.
• char zz = 'a';: Declares a character variable named zz and initializes it with the character 'a'.

Basic Operators in C

• The assignment operator (=) assigns the value on the right-hand side to the variable on the left-hand side.
• Basic arithmetic operators:
  • +: Addition
  • -: Subtraction
  • *: Multiplication
  • /: Division
  • %: Modulo (remainder of division)

Advanced Operators in C

• ++: Increments a variable by 1.
• --: Decrements a variable by 1.
• These operators are not used with floating-point numbers.
• i++: Increments i after using its current value.
• ++i: Increments i before using its value.
• 'a' + 1: Valid operation in C, it yields the next character in the ASCII sequence after 'a'.

Test your knowledge of fundamental C programming concepts, including boolean tests with integers, variable naming conventions, and variable declarations. This quiz covers important rules and data types essential for writing clear and correct C code.