Ansi c file size

Note that the first argument should be in the range of an unsigned char so that it is a valid character. The second argument is the file to write to.

On success, fputc will return the value c, and on failure, it will return EOF. Both of these functions deal with blocks of memories - usually arrays.

Because they accept pointers, you can also use these functions with other data structures; you can even write structs to a file or a read struct into memory. Web This Site. Or the header does exist. But in that case, the contents are not known as far as ISO C is concerned; no such header is documented for the Library.

In this case, the include directive brings in an unknown chunk of code, incorporating it into the translation unit. It is impossible to define the behavior of an unknown chunk of code. Stack Overflow for Teams — Collaborate and share knowledge with a private group.

Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. Ask Question. Asked 9 years, 9 months ago. Active 7 years, 1 month ago. Viewed 11k times. Improve this question. Please note that the article you linked to is Considered Harmful. The stat -based alternative will fail to determine sizes of some non-regular-files that do have well-defined sizes, such as block devices disk partitions, etc. It's not useful but Add a comment. Active Oldest Votes. Improve this answer.

Carl Norum Carl Norum k 30 30 gold badges silver badges bronze badges. Unfortunately it also doesn't provide any other options. Maybe it doesn't have to. You can fread or fgetc until EOF , which isn't fast, but should work and be more portable. Binary files have an exact size and you can seek relative to the end.

There is no solution for undefined behavior in solving this problem. Solving this problem, and most other everyday problems, requires removing the ISO C blinders from one's eyes.

Show 2 more comments. It doesn't mean it's undefined behaviour to do so. But if the stream supports it, it's ok. Martinho Fernandes R. Martinho Fernandes k 69 69 gold badges silver badges bronze badges. The last paragraph is not quite right. You can use the fopen function to create a new file or to open an existing file. This call will initialize an object of the type FILE , which contains all the information necessary to control the stream. Opens a text file for writing.

If it does not exist, then a new file is created. Here your program will start writing content from the beginning of the file. Opens a text file for writing in appending mode. Here your program will start appending content in the existing file content.

Opens a text file for both reading and writing. It first truncates the file to zero length if it exists, otherwise creates a file if it does not exist. It creates the file if it does not exist. If you're on windows, you should use GetFileSizeEx - it actually uses a signed 64 bit integer, so they'll start hitting problems with 8 exabyte files.

Foolish Microsoft! Update: This isn't really the best solution. Change the definition to int so that error messages can be transmitted, and then use fseek and ftell to determine the file size. Note : It limits the size to 4GB. If not Fat32 filesystem then use the 64bit version! We'll have to use our mind.

For now, we'll use the seek approach!