Size of data in C++ (memory occupied)

Summary

In C++, understanding the size of data types and how they occupy memory is crucial to writing efficient code. This article will introduce the sizes of different data types in C++ and how to calculate the memory space they occupy.

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In C++, each data type has a different byte size, depending on the compiler and operating system implementation. Here are some common data types and their sizes in bytes in standard C++:

1. Basic data types:

• bool: Usually occupies 1 byte.
• char: Usually occupies 1 byte, representing one character.
• int: Usually occupies 4 bytes and represents an integer.
• float: Usually occupies 4 bytes and represents a single-precision floating point number.
• double: Usually occupies 8 bytes and represents a double-precision floating point number.

2. Arrays:
   Arrays in C++ consist of elements of the same type. The size of the array depends on the size of the element type and the length of the array. For example, an array containing 10 intelements of type will occupy 40 bytes (assuming inta size of 4 bytes).

3. Structures and classes:
   Structures and classes are custom data types that can contain multiple member variables. The size of structures and classes depends on the size of individual member variables and the compiler's memory alignment rules. By default, the compiler aligns structure and class member variables to improve memory access efficiency.

4. Pointers and references:
   Pointers and references themselves are fixed in size, usually taking up 4 or 8 bytes, depending on the number of bits on the platform. But the size of the object they point to is not included in the size of the pointer or reference.

Get the size of a data type

You can use sizeofoperators to get the size of a data type, for example:

int main() {
    
    
    cout << "Size of int: " << sizeof(int) << " bytes" << endl;
    return 0;
}

Notice

It should be noted that different compilers and operating systems may have different sizes of data types. In addition, the size of some data types may be limited by the compiler and operating system, such as long longand long doubleetc.

When designing and developing C++ applications, understanding the size of data types is critical for memory management and performance optimization. Reasonable use of data types can reduce memory usage and improve code execution efficiency.

in conclusion

This article introduces the sizes of common data types in C++ and their memory usage. By understanding the size of data types, we can better control memory usage and write more efficient code. In actual development, it is recommended to use sizeofoperators to obtain the size of the data type and perform appropriate memory optimization as needed.

I hope this article can help you deal with data size issues in C++. If you have more questions, please feel free to ask.