When writing in C, how can I tell how much stack space is available in memory when I launch a program? How about heap space?
How can I tell how much memory is being used during the execution of my program?
Share
Sign Up to our social questions and Answers Engine to ask questions, answer people’s questions, and connect with other people.
Login to our social questions & Answers Engine to ask questions answer people’s questions & connect with other people.
Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Please briefly explain why you feel this question should be reported.
Please briefly explain why you feel this answer should be reported.
Please briefly explain why you feel this user should be reported.
When writing in C, how can I tell how much stack space is available in memory when I launch a program? How about heap space?
How can I tell how much memory is being used during the execution of my program?
This is all Win32-specific (not really C-specific, all just OS API):
When a thread is created, it gets 1MB stack space by default, by that can be modified in whatever CreateThread API you use.
You can peek into the thread information block to find the actual stack info, but even though this is documented, this technique isn’t officially supported, see http://en.wikipedia.org/wiki/Win32_Thread_Information_Block .
Also, for a 32-bit application, you can only address up to 2GB, so for an app that by design uses lots of memory, then the thing to watch out for is the total size of the process’ virtual address space (committed + reserved), which includes all heap allocations. You can programmatically access the process’ virtual memory with the GlobalMemoryStatusEx API, look at the ullTotalVirtual param for virtual address space. Once your process gets close to 1.8 or 1.9GB of VAS, then heap allocations and VirtualAlloc calls begin to fail. For “normal” apps, you don’t have to worry about running out of VAS, but it’s always good to check for fail allocs. Also, you shouldn’t get a stack overflow, unless you have a bug, or a bad design.