C sizeof Operator Explained: Byte Calculation

In C language, the sizeof operator is used to calculate the byte length of a data type or variable. Its syntax is sizeof(type) or sizeof(expression), where type represents the data type, and expression represents the variable or expression.

The result returned by the sizeof operator is an unsigned int value, representing the number of bytes occupied by a data type or variable. For example, sizeof(int) returns 4, indicating that an int type occupies 4 bytes.

When calculating the length of an array, the sizeof operator can be directly applied to the array variable, returning the total number of bytes occupied by the entire array. For example, for an int array arr[5], sizeof(arr) returns 20, indicating that the entire array occupies 20 bytes.

It is important to note that the sizeof operator calculates at compile time without actually computing the operand. Therefore, the sizeof operator cannot be used on pointers, as pointers store addresses, not data. If you need to calculate the byte length of the data type pointed to by a pointer, you can achieve this by dereferencing the pointer.