What is a portable method to find the maximum value of size_t?

c size-t
Justicle picture Justicle · Aug 12, 2010 · Viewed 30.2k times · Source

I'd like to know the maximum value of size_t on the system my program is running. My first instinct was to use negative 1, like so:

size_t max_size = (size_t)-1;

But I'm guessing there's a better way, or a constant defined somewhere.

Answer

AnT picture AnT · Aug 12, 2010

A manifest constant (a macro) exists in C99 and it is called SIZE_MAX. There's no such constant in C89/90 though.

However, what you have in your original post is a perfectly portable method of finding the maximum value of size_t. It is guaranteed to work with any unsigned type.

Related questions

What is size_t in C?

I am getting confused with size_t in C. I know that it is returned by the sizeof operator. But what exactly is it? Is it a data type? Let's say I have a for loop: for(i = 0; i < …

Read More
unsigned int vs. size_t

I notice that modern C and C++ code seems to use size_t instead of int/unsigned int pretty much everywhere - from parameters for C string functions to the STL. I am curious as to the reason for this …

Read More
What's sizeof(size_t) on 32-bit vs the various 64-bit data models?

On a 64-bit system, sizeof(unsigned long) depends on the data model implemented by the system, for example, it is 4 bytes on LLP64 (Windows), 8 bytes on LP64 (Linux, etc.). What's sizeof(size_t) supposed to be? Does it vary with …

Read More