C where is sizeof defined

The sizeof operator can be used in two forms. First, to get size of an object that can be a variable or array or structure. Second, to get size of a type name that can be the name of a basic type like int or double , or a derived type like a structure or a pointer.

The following expressions shows the syntax of sizeof. The sizeof operator yields an integer equal to the size of the specified object or type in bytes. Sizeof operator in C is machine-dependent functionality which varies from compiler to compiler. It can be said that it is a byte specific functionality. It helps in providing the byte and size of the variables and the number it occupies for the allocation of the variable to the memory.

Sizeof function is exclusively used to find out the exact size of a type of the variable used for programming in C. It is very useful in the implementation and development of portable applications as it is very flexible and easy to adopt for its versatility. It is not at all compiler-specific and thus varies from compiler to compiler.

It compiles any unary data type and then used for computing the size of its operand. It returns the size of a variable. If a machine is 32 bits, then the memory allocation and other computation will work in the same way in a manner that the output will vary with a bit machine and if it is 64 bits then it will vary with the 64 bits.

Learn to implement data structures like Heap, Stacks, Linked List and many more! Check out our Data Structures in C course to start learning today. When operand is an expression. When sizeof is used with the expression, it returns size of the expression. The final result will be a double, Hence the output of our program is 8 bytes.

Type of operator sizeof is a compile time operator. Lets see an example. This is because, x is incremented inside the parentheses and sizeof is a compile time operator. Need of Sizeof 1. In the above code, we are printing the size of different data types such as int, char, float with the help of sizeof operator.

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