comparison

问题 I make a comparison of two strings which are obviously identical. Unfortunately my if clause doesn´t work as expected: NSLog(@"%@ == %@ ?",strippedString1,strippedString2); if (strippedString1 == strippedString2) { [_newBuild setTextColor: [NSColor greenColor] ]; [_OldBuild setTextColor: [NSColor greenColor] ]; } This is my NSLog output: Build: 2A12-046 == Build: 2A12 Even a byte by byte comparison says both strings are identical: Any clues ? 回答1: With == you are comparing pointer address, to

问题 I found a comment today in a source file: // - no longer compare BOOL against YES (dangerous!) Is comparing BOOL against YES in Objective-C really that dangerous? And why is that? Can the value of YES change during runtime? Maybe NO is always 0 but YES can be 1 , 2 or 3 - depending on runtime, compiler, your linked frameworks? 回答1: The problem is that BOOL is not a native type, but a typedef: typedef signed char BOOL; #define YES (BOOL)1 #define NO (BOOL)0 As a char, its values aren't

问题 Closed . This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed 2 years ago . I am trying to show where the two HTML pages differ. I am trying to figure out a way if i can compare the HTML source code of two webpages(almost similar), and show/highlight the differences visually(on UI). What I tried: I thought of taking snapshot of the page and then use

问题 I'm trying to port some code from Python 2 to Python 3. It's ugly stuff but I'm trying to get the Python 3 results to be as identical to the Python 2 results as possible. I have code similar to this: import json # Read a list of json dictionaries by line from file. objs = [] with open('data.txt') as fptr: for line in fptr: objs.append(json.loads(line)) # Give the dictionaries a reliable order. objs = sorted(objs) # Do something externally visible with each dictionary: for obj in objs: do

问题 This question already has answers here : Are Variable Operators Possible? (6 answers) Closed 4 years ago . Similar to python: make a variable equal an operator (+,/,*,-) I've got a bit of code where the user can pick a type of comparison to be run, and a value to compare against. I'm curious to know if there's any way in Javascript to turn that user provided comparison value into an actual comparison, allowing me to do something like: if (user_val user_comparison other_val) { do_something();

问题 Here is the code I am looking at. foreach ($header as $idx => $field) { if (stripos($field, 'foo') !== false) { $cols['foo'] = $idx; } else if (stripos($field, 'bar') !== false) { $cols['bar'] = $idx; } else if (stripos($field, 'brr') !== false) { $cols['brr'] = $idx; } else if (stripos($field, 'ffo') !== false) { $cols['ffo'] = $idx; } } Sorry, don't know how to format the code prettily either, any tips on that would be appreciated. I am looking at some code written by someone much smarter

问题 Here is the code I am looking at. foreach ($header as $idx => $field) { if (stripos($field, 'foo') !== false) { $cols['foo'] = $idx; } else if (stripos($field, 'bar') !== false) { $cols['bar'] = $idx; } else if (stripos($field, 'brr') !== false) { $cols['brr'] = $idx; } else if (stripos($field, 'ffo') !== false) { $cols['ffo'] = $idx; } } Sorry, don't know how to format the code prettily either, any tips on that would be appreciated. I am looking at some code written by someone much smarter

问题 Is there a standard value for (or method for obtaining) epsilon in Python? I need to compare floating point values and want to compare against the smallest possible difference. In C++ there's a function provided numeric_limits::epsilon( ) which gives the epsilon value for any given data type. Is there an equivalent in Python? 回答1: The information is available in sys.float_info, which corresponds to float.h in C99. >>> import sys >>> sys.float_info.epsilon 2.220446049250313e-16 回答2: As strcat

问题 I use Java where we only have packages. I know there are other programming languages that also include modules. What's the difference? 回答1: It's hard to compare semantics in the void. (What other languages do you mean?) A "module" might be analogous to a Java class, or a Java package, or something else entirely, depending on that other language. Typically since "modules" tend to be from procedural languages, I'd lean toward saying Java class, but I think the line is very fuzzy at that point

问题 I use Java where we only have packages. I know there are other programming languages that also include modules. What's the difference? 回答1: It's hard to compare semantics in the void. (What other languages do you mean?) A "module" might be analogous to a Java class, or a Java package, or something else entirely, depending on that other language. Typically since "modules" tend to be from procedural languages, I'd lean toward saying Java class, but I think the line is very fuzzy at that point