The meaning of sizeof in c language

The sizeof operator in C language returns the memory size occupied by the type of expression, including data types, variables and constants. It helps to understand variable or type memory size, dynamic memory allocation and creation of arrays of specified size.

The meaning of sizeof in C language

sizeof is an operator in C language that returns an expression The memory size of the type. It is a unary operator, which means it accepts only one operand.

sizeof's syntax:

sizeof(表达式)

where the expression can be a data type, variable or constant.

The return value of sizeof:

The sizeof operator returns a value of type size_t, which is defined as an unsigned integer and is used to store the memory size.

Uses of sizeof:

The sizeof operator has the following uses:

• Determine the memory size of a variable or type : It helps programmers understand the space occupied by certain variables or data types in memory.
• Dynamic memory allocation: It is used to determine the amount of memory allocated for dynamically allocated memory blocks.
• Create array: It can be used to declare and create an array of specified size.

Example:

int main() {
    int i;
    double d;

    printf("sizeof(int): %d\n", sizeof(int));
    printf("sizeof(double): %d\n", sizeof(double));

    return 0;
}

Output:

sizeof(int): 4
sizeof(double): 8

In the example, sizeof(int) returns 4, indicating that the int type is in memory Occupies 4 bytes. sizeof(double) returns 8, indicating that the double type occupies 8 bytes in memory.

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