22

Jul

C FAQ: What are the sizes of char, short, int and long?

Posted by   Published in C, Technical

What are the sizes of char, short, int and long?

The C standard does not provide standard sizes for these data types! Hence the sizes will always be implementation dependent, which means different compilers can give different sizes. That said, there are some rules however that all compilers are obliged to follow:

1. The size of char should be at least 1 byte (most implementations will have sizeof(char)=1)

2. The size of short should be less than or equal to the size of int, and should be at least 2 bytes (most implementations will have sizeof(short)=2)

3. The size of int should be the machine word size (the optimal size that the system can handle at one go). Thus, a 16-bit compiler will have sizeof(int)=2 (16 bits = 2 bytes) whereas a 32-bit compiler will have sizeof(int)=4 (32 bits = 4 bytes)

4. The size of long should be greater than or equal to size of int, and should be at least 4 bytes (most implementations will have sizeof(long=4)

Thus, the following condition will always hold good, no matter which C compiler you use:

sizeof(char) <= sizeof(short) <= sizeof(int) <= sizeof(long)

Typical values are shown below:

char short int long
16-bit platform 1 2 2 4
32-bit platform 1 2 4 4
64-bit platform 1 2 8 8

 

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