Size ints and longs?

Question

I wrote this code:

#include <stdio.h> int main(){ printf("Size of short int: %d \n", sizeof(short)); printf("Size of int: %d \n", sizeof(int)); printf("Size of long int: %d \n", sizeof(long)); printf("Size of float: %d \n", sizeof(float)); printf("Size of double: %d \n", sizeof(double)); printf("Size of long double: %d \n", sizeof(long double)); return 0; } 

If the solution was:

 Size of short int: 2 Size of int: 4 Size of long int: 4 Size of float: 4 Size of double: 8 Size of long double: 12 

Naturally, there are differences between integers and floating point data types, but what is the reason that any compiler allocates the same amount of memory to the same length as for int? Long was designed to handle large values, but is useless if you do the same as above (for an integer). Floating point diversity adds an additional 16 bits of distribution.

My question, in fact, is why are there long ones if there are instances of machines that do not use their capabilities?

From the book K & R:

 The intent is that short and long should provide different lengths of integers where practical; int will normally be the natural size for a particular machine. short is often 16 bits long, and int either 16 or 32 bits. Each compiler is free to choose appropriate sizes for its own hardware, subject only to the the restriction that shorts and ints are at least 16 bits, longs are at least 32 bits, and short is no longer than int, which is no longer than long. 

Is there a "thumb rule" if you want when the machine compiler wants to allocate more memory for longer than int? And vice versa? What are the criteria?

Answer 1

Is there a "thumb rule" if you want when the machine compiler will allocate more memory for longer than int? And the vices of Versa? What are the criteria?

The criterion will most likely be: "Will the target machine use a larger type?" or "Does the target machine have its own registers and / or instructions that work with this larger type?"

Answer 2

Why have the long if there will be instances of machines that make no use of its abilities? Because some cars will use their capabilities.

Answer 3

"int" is at least 16 bits, and "long int" is at least 32 bits.

"int" can contain values ​​up to 32,767, and "long int" can contain values ​​up to 2,147,483,647.

In the header file limits.h you can find the maximum and minimum values ​​for the respective machines.

Answer 4

On 32-bit and higher bit machines, the size of long is equal to the size of int, which is 32 bits. On 16-bit machines, the size is short equal to the size of int, which is 16 bits, and the size of the long is 32 bits. Thus, on 16-bit machines, the length is 32 bits, which may contain a larger range than short and bit.