C Datatype

Abstract

---

Uninitialised variables

Uninitialised variables in C contain unknown values, unlike Java which sets $0$ for uninitialised Primitive Datatype!

How to find the spaces used by a datatype?

sizeof(int) returns the size of int in the current machine.

Importance of explicit datatype

C uses the data type to determine the underlying instruction to be generated. Different instructions are used to handle floating-point numbers and integers.

What is char in C?

Char is basically a 8-bit integer, but usually used to hold a character using ascii table.

Everything in C is an number!

No boolean type in ANSI C!

0 is used to represent false, any other value is used to represent true.

int size

int was designed to match the word size of the machine, so it was 16 bits on 16-bit machines, 32 bits on 32-bit machines, and so on.

C Mixed-type Arithmetic Operation

---

1. 10/4.0 will give us float 2.0, but if we int p = 10/4.0, p will have a value of 2 which converts from float 2.0 to int 2
2. 10 / 4.0 involves a float operand, so the result is the floating-point value 2.5. If you assign this to an int variable like int p = 10 / 4.0, the fractional part is truncated, and p will store the integer value 2.

Type Casting in C

1. float p = (float) 6 / 4 will result in p = 1.5. The (float) explicitly converts the integer 6 to a float before the division occurs. This ensures that floating-point division is performed, yielding a floating-point result
2. float p = (float) (6 / 4) will result in p = 1.0. The expression within the parentheses (6 / 4) is evaluated first. Since both operands are integers, integer division is performed, resulting in 1. This integer value is then converted to a float using the (float) cast.