Define unary operator explain different unary operators used in c language?

Answer 1

A unary operator is one that requires only one operand. The unary operators are the prefix and postfix increment and decrement, positive and negative, logical and bitwise negation, and address and indirection operators, plus the words alignof, typeof, and sizeof.

The first two operators are increment "++", and decrement "--". Its position before or after the variable determines prefix or postfix. Incrementing increases the stored value by 1, and decrementing decreases the stored value by 1. If it is to the left of the variable, the operation occurs before the variable is used; if it is to the right, it occurs after the variable is used.

The positive operator "+" simply asserts the current value, and exists as acomplementto the negation operator "-". The negation operator returns the number with the opposing sign. If x is 5, then -x is -5, and if x is -5, then -x is 5.

The logical negation "!" and bitwise negation "~" operators perform actions on individual bits. C considers zero to be false, and all other values to be true. Using logical negation, it returns true if the value is zero, or false for any other value. The bitwise negation changes all 1 bits to 0 bits, and 0 bits to 1 bits. For an unsigned byte, ~0 becomes 255, and ~255 becomes 0. For signed variables, ~0 would become -1, and ~-1 would become 0. This is because of the two's complement method of signed numbers.

Address "&" and indirection "*" operators take the address or value of the operand. The address operator allows a variable to be passed by reference; modifying the reference will modify the original value. Using the indirection operator treats a variable as a memory address, which allows the programmer to access a specific spot in memory.

Alignof, sizeof, and typeof are all used to determine the alignment, size, and type of objects dynamically. This is necessary when trying to determine how data is laid out when there may be differences in memory accesses across platforms (e.g. when reading a ZIP file's directory contents).