c min function header in c

stackoverflow.com › questions › 3437404 › min-and-max-in-c

Where are MIN and MAX defined in C, if at all?

They aren't.

What is the best way to implement these, as generically and type safe as possible (compiler extensions/builtins for mainstream compilers preferred).

As functions. I wouldn't use macros like #define MIN(X, Y) (((X) < (Y)) ? (X) : (Y)), especially if you plan to deploy your code. Either write your own, use something like standard fmax or fmin, or fix the macro using GCC's typeof (you get typesafety bonus too) in a GCC statement expression:

 #define max(a,b) \
   ({ __typeof__ (a) _a = (a); \
       __typeof__ (b) _b = (b); \
     _a > _b ? _a : _b; })

Everyone says "oh I know about double evaluation, it's no problem" and a few months down the road, you'll be debugging the silliest problems for hours on end.

Note the use of __typeof__ instead of typeof:

If you are writing a header file that must work when included in ISO C programs, write __typeof__ instead of typeof.

Answer from David Titarenco on Stack Overflow

Stack Overflow

stackoverflow.com › questions › 3437404 › min-and-max-in-c

MIN and MAX in C - Stack Overflow

Top answer

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546

Where are MIN and MAX defined in C, if at all?

They aren't.

What is the best way to implement these, as generically and type safe as possible (compiler extensions/builtins for mainstream compilers preferred).

As functions. I wouldn't use macros like #define MIN(X, Y) (((X) < (Y)) ? (X) : (Y)), especially if you plan to deploy your code. Either write your own, use something like standard fmax or fmin, or fix the macro using GCC's typeof (you get typesafety bonus too) in a GCC statement expression:

 #define max(a,b) \
   ({ __typeof__ (a) _a = (a); \
       __typeof__ (b) _b = (b); \
     _a > _b ? _a : _b; })

Everyone says "oh I know about double evaluation, it's no problem" and a few months down the road, you'll be debugging the silliest problems for hours on end.

Note the use of __typeof__ instead of typeof:

If you are writing a header file that must work when included in ISO C programs, write __typeof__ instead of typeof.

2 of 16

129

It's also provided in the GNU libc (Linux) and FreeBSD versions of sys/param.h, and has the definition provided by dreamlax.

On Debian:

$ uname -sr
Linux 2.6.11

$ cat /etc/debian_version
5.0.2

$ egrep 'MIN\(|MAX\(' /usr/include/sys/param.h
#define MIN(a,b) (((a)<(b))?(a):(b))
#define MAX(a,b) (((a)>(b))?(a):(b))

$ head -n 2 /usr/include/sys/param.h | grep GNU
This file is part of the GNU C Library.

On FreeBSD:

$ uname -sr
FreeBSD 5.5-STABLE

$ egrep 'MIN\(|MAX\(' /usr/include/sys/param.h
#define MIN(a,b) (((a)<(b))?(a):(b))
#define MAX(a,b) (((a)>(b))?(a):(b))

The source repositories are here:

GNU C Library
FreeBSD

Linux Hint

linuxhint.com › min-function-c

MIN() Macro in C Language – Linux Hint

To do this, we include the “stdio.h” and “param.h” headers and open a main() function of type void. We define the “a” and “b” integers in it and assign them with a random value. We also define the “c” integer to store the result. Then, we call the macro MIN() and pass “a” and “b” as input arguments and “c” as the output argument.

Discussions

min/max in *c*

But what is the proper header to include for min & max? Your framerate proves your lack of manhood ... Macros are dangerous in this situation because a or b will get evaluated twice, which would cause unexpected behavior on expressions whose evaluation has side effects (like a function... More on gamedev.net

gamedev.net

8

July 29, 2008

c++ min and max from algorithm work without including this header, how?

Blind shot into the dark here as I'm not very familiar with C++ libraries, but it seems that according to: https://code.woboq.org/gcc/libstdc++-v3/include/std/functional.html functional has an include for which seems to be the header file for algorithm. So, I'm guessing that by including functional you're also including the files it includes. One of those includes happens to be algorithm so you're allow to use it. link to the algorithm header file: https://code.woboq.org/gcc/libstdc++-v3/include/bits/stl_algo.h.html More on reddit.com

r/learnprogramming

6

3

December 3, 2021

How Do Header Files Work in C/C++?

The convention in C/C++ when implementing a module/library is to divide it into headers (.h) and source files (.c, .cc, .cpp). You typically include only the bare minimum interface in the header file. That means things like class/struct definitions, function prototypes, and global constants. Then the implementations of said functions are placed in a corresponding source file. When making the module available to the public, you would compile the source files into binaries (often .so or .dll depending on operating system) and deliver the .h files along with the .so files. As a user of one of these libraries you need to do two things to properly use it: include the header file in your source (e.g. #include ) when compiling your code, tell the linker where to find the implementation binaries that correspond to the headers. (e.g. gcc myCoolFile.c -l myCoolOtherFile). Side note: when you install a library it typically places the .h and .so files in directories where your compiler will look for them by default (on Linux, somewhere like /usr/include and /usr/lib/) so providing just the name of the library is usually sufficient for both of the above steps. One of the benefits to packaging libraries in this way is to save compilation time. Imagine having to include the source code (.c files) for every library you used (stdio.h, stdlib.h, etc) in every project. You would need to compile each of those every time and each is potentially a massive amount of code. By using libraries as pre-compiled binaries and headers you get to save a lot of compilation time. More on reddit.com

r/learnprogramming

23

10

November 28, 2022

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