Operators, Expressions, and Data Input/Output

1. Operators and Expressions

Arithmetic Operators

Arithmetic operators are used to perform basic mathematical operations:

• + (Addition): Adds two values.
  • Example: x + y adds x and y.
• - (Subtraction): Subtracts one value from another.
  • Example: x - y subtracts y from x.
• * (Multiplication): Multiplies two values.
  • Example: x * y multiplies x and y.
• / (Division): Divides one value by another.
  • Example: x / y divides x by y.
• % (Modulus): Returns the remainder of division.
  • Example: x % y returns the remainder when x is divided by y.

Unary Operators

Unary operators operate on a single operand to perform operations like incrementing or decrementing a value:

• ++ (Increment): Increases a value by 1.
  • Example:

  x++;  // Increment x by 1.
• -- (Decrement): Decreases a value by 1.
  • Example:

  x--;  // Decrement x by 1.

Relational and Logical Operators

These operators are used to compare values and combine conditions:

• Relational Operators: Compare two values:
  • == (Equal to): Returns true if both operands are equal.
  • != (Not equal to): Returns true if operands are not equal.
  • < (Less than): Returns true if left operand is less than the right.
  • > (Greater than): Returns true if left operand is greater than the right.
• Logical Operators: Combine multiple boolean expressions:
  • && (Logical AND): True if both operands are true.
  • || (Logical OR): True if at least one operand is true.
  • ! (Logical NOT): Inverts the truth value of the operand.

Assignment Operators

Assignment operators are used to assign values to variables:

• =: Assigns a value to a variable.
  • Example:

  a = 5;  // Assigns 5 to a.
• Shorthand Assignment:
  • +=, -=, *=: Update the value of a variable using the current value.
  • Example:

  a += 5;  // Equivalent to a = a + 5;

Conditional Operator (?:)

The conditional operator is a shorthand for if-else statements:

• Example:

result = (a > b) ? a : b;  // If a > b, result = a; else, result = b.

Library Functions

Library functions are predefined functions provided by C to perform common tasks:

• Example:
  • printf() for printing output to the console.
  • scanf() for reading input from the user.

2. Data Input and Output

Single Character Input/Output

Functions used for handling single characters in C:

• getchar(): Reads a single character from standard input.
  • Example:

  char c = getchar();  // Reads a character from input.
• putchar(): Outputs a single character to standard output.
  • Example:

  putchar(c);  // Outputs the character c.

Formatted Input/Output

Functions for reading and writing formatted data:

• scanf(): Reads formatted input from the user.
  • Example:

  scanf("%d", &x); // Reads an integer and stores it in x.
• printf(): Prints formatted output to the screen.
  • Example:

  printf("x = %d", x); // Prints the value of x.

Gets and Puts Functions

Functions for handling strings:

• gets(): Reads a string from the user (Note: gets() is unsafe and has been removed in C11; use fgets() instead).
  • Example:

  gets(str);  // Reads a string into str.
• puts(): Outputs a string to the console.
  • Example:

  puts(str);  // Prints the string str.