local-variables

Why can this code run successfully in Code::block. The IDB just reports warning: "reference to local variable ‘tmp’ returned", but ouput the result "hello world" successfully. #include <iostream> #include<string> using namespace std; const string &getString(const string &s) { string tmp = s; return tmp; } int main() { string a; cout<<getString("hello world")<<endl; return 0; } prvit Maybe this link will help you. Upon leaving a function, all local variables are destroyed. By returning a reference to tmp , you are returning a reference to an object that soon ceases to exist (that is,

I have this simple line of code: int x; x automatically has the value of 1. I don't set it to anything but when I debug, it shows that x is 1. Does an int have a default value of 1?! No. int has an undefined default value. It just happens to be 1 in this case. It could just as easily be -18382 or 22 or 0xBAADF00D . Always initialize your variables in C. The initial value is undefined, and in this case will be whatever happened to be in that memory location before x started using it. (Depending on the surrounding code, you might find that in your specific case it's always 1 , but you can't be

So this is an odd one, I know the code itself is fairly useless, but what I'm wondering why I get the error: I was writing some code, I had written this: if(scan.hasNextInt()) int row = scan.nextInt(); Wasn't thinking about variable scope at the time, obviously this is useless because I can't use row past the if anyway. What I don't get is why I got the error I did: > javac hw.java hw.java:25: '.class' expected int row = scan.nextInt(); ^ hw.java:25: not a statement int row = scan.nextInt(); ^ hw.java:25: illegal start of expression int row = scan.nextInt(); ^ hw.java:25: ';' expected int row

If I execute this ruby code: def foo 100 end p defined?(foo), foo if false foo = 200 end p defined?(foo), foo The output I get is: "method" 100 "local-variable" nil Can someone explain to me why foo is set to nil after not executing the if? Is this expected behavior or a ruby bug? Names on the left hand side of assignments get set to nil , even if the code can't be reached as in the if false case. >> foo NameError: undefined local variable or method `foo' for main:Object ... >> if false .. foo = 1 .. end #=> nil >> foo #=> nil When Ruby tries to resolve barewords, it first looks for local

in Java android application how can i access variables of outer class from the inner anonymous class ? Example: ProgressDialog dialog = new ProgressDialog(this); ..... send.setOnClickListener(new View.OnClickListener() { public void onClick(View v) { //here i'd like to do something with **dialog** variable ....... } }); If the dialog variable is a field of the outer class, you can use this prefixed with the outer class name ( a qualified this ): send.setOnClickListener(new View.OnClickListener() { public void onClick(View v) { ProgressDialog dlg = OuterClass.this.dialog; ....... } });

Same in Ruby 1.8.7 and 1.9.2: $ irb ruby-1.8.7-p302 > foo.nil? NameError: undefined local variable or method `foo' for #<Object:0x3794c> from (irb):1 ruby-1.8.7-p302 > @bar.nil? => true ruby-1.8.7-p302 > @@wah.nil? NameError: uninitialized class variable @@wah in Object from (irb):3 why the instance variable treated differently than a local and class variable? In Ruby, most uninitialized or even non-existing variables evaluate to nil . This is true for local variables, instance variables and global variables: defined? foo #=> nil local_variables #=> [] if false foo = 42 end defined? foo #=>

Sorry for this question, but this issue really screwed up my day. The following Code alerts 10 as it should: var globalId='10'; function check(){ alert(globalId); } check(); But this next code alerts undefined : var globalId='10'; function check(){ alert(globalId); var globalId; } check(); I am aware that if I declare a variable in a function its a local variable, but if I already declared it as global, how can it be that my alerts says undefined ? This is an easy example, but in my original code I did a lot of stuff in between the beginning of the function, then a long way down I checked to