How would you define a simple "min" method in obj-c

user_257595 0
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I want to define a min and max methods in a Utils class.

@interface Utils

int min(int a, int b);
int max(int a, int b);

@end

But I don't want to have named parameters. It would be a too heavy notation. I wanted to use the C-style definition. But then [Utils min(a, b)] as a call doesn't work. What is my problem?

Thanks in advance for any help

max min methods objective-c c
7 Answers

It is already defined as a macro. 

MIN(a, b)

MAX(a, b)

You dont need to redefine these ones.

user_1456450

Since you aren't using the OS X Implementation of objective-c, you may not have access to the predefined MIN and MAX macros.

You can define these yourself as

#define MIN(a,b)    ((a) < (b) ? (a) : (b))
#define MAX(a,b)    ((a) > (b) ? (a) : (b))

There is probably a better way to define them, but these will create the simple macros for your use. You can add them into any common .h file that your classes normally share.

user_1205870

This is probably not a good idea for this particular application, but it is possible to write Objective-C methods with parameters “without names”, or rather with zero-length names:

+ min:(int)a :(int)b;
...
[Utils min:a :b]

(The selector would be @selector(min::).)

user_996920

Objective-C class methods use named parameters, period. That's just the way it is.

Why not make it a global, free function? You shouldn't need a Utils class for this kind of thing.

If you don't want to clutter the global namespace, you could use Objective-C++ (rename all .m files to .mm) and put it in a namespace.

user_1202780

Here is a macro I created for multi-max and multi-min which allows more than just 2 inputs.

float a = MMAX(1,2,9.33,2.5); //a = 9.33

The internal mechanisms use long double and you'll just cast the output to whatever variable you're using. I'd prefer a solution using typeof but couldn't figure out how to do it on __VA_ARGS__ on a per argument basis, maybe someone more versed than me in C can figure it out and comment? Anyways, here's the macro definition:

#define MMAX(...) ({\
long double __inputs[(sizeof((long double[]){__VA_ARGS__})/sizeof(long double))] = {__VA_ARGS__};\
long double __maxValue = __inputs[0];\
for (int __i = 0; __i < (sizeof((long double[]){__VA_ARGS__})/sizeof(long double)); ++__i) {\
long double __inputValue = __inputs[__i];\
__maxValue = __maxValue>__inputValue?__maxValue:__inputValue;\
}\
__maxValue;\
})

#define MMIN(...) ({\
long double __inputs[(sizeof((long double[]){__VA_ARGS__})/sizeof(long double))] = {__VA_ARGS__};\
long double __minValue = __inputs[0];\
for (int __i = 0; __i < (sizeof((long double[]){__VA_ARGS__})/sizeof(long double)); ++__i) {\
long double __inputValue = __inputs[__i];\
__minValue = __minValue<__inputValue?__minValue:__inputValue;\
}\
__minValue;\
})
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