I have an XSTRING variable, but i can't find a way to find it's length (in bytes, preferrably).
It seems that when an XSTRING is returned/exported from a method or function module, its length is usually also exported. But in my case i only have the string itself.
Is there a way to figure out the length?
I'd say you're looking for xstrlen( l_my_xstring )
Related
I need to store an alphanumeric string in an integer column on one of my models.
I have tried:
#result.each do |i|
hex_id = []
i["id"].split(//).each{|c| hex_id.push(c.hex)}
hex_id = hex_id.join
...
Model.create(:origin_id => hex_id)
...
end
When I run this in the console using puts hex_id in place of the create line, it returns the correct values, however the above code results in the origin_id being set to "2147483647" for every instance. An example string input is "t6gnk3pp86gg4sboh5oin5vr40" so that doesn't make any sense to me.
Can anyone tell me what is going wrong here or suggest a better way to store a string like the aforementioned example as a unique integer?
Thanks.
Answering by request form OP
It seems that the hex_id.join operation does not concatenate strings in this case but instead sums or performs binary complement of the hex values. The issue could also be that hex_id is an array of hex-es rather than a string, or char array. Nevertheless, what seems to happen is reaching the maximum positive value for the integer type 2147483647. Still, I was unable to find any documented effects on array.join applied on a hex array, it appears it is not concatenation of the elements.
On the other hand, the desired result 060003008600401100500050040 is too large to be recorded as an integer either. A better approach would be to keep it as a string, or use different algorithm for producing a number form the original string. Perhaps aggregating the hex values by an arithmetic operation will do better than join ?
I was looking for a way to enumerate String types in (vb).NET, but .NET enums only accept numeric type values.
The first alternative I came across was to create a dictionary of my enum values and the string I want to return. This worked, but was hard to maintain because if you changed the enum you would have to remember to also change the dictionary.
The second alternative was to set field attributes on each enum member, and retrieve it using reflection. Surely enough this worked aswell and also solved the maintenance problem, but it uses reflection and I've always read that using reflection should be a last resort thing.
So I started thinking and I came up with this: every ASCII character can be represented as a hexadecimal value, and you can assign hexadecimal values to enum members.
You could get rid of the attributes, assign the hexadecimal values to the enum members. Then, when you need the text value, convert the value to a byte array and use System.Text.Encodings.ASCII.GetString(enumMemberBytes) to get the string value.
Now speaking out of experience, anything I come up with is usually either flawed or just plain wrong. What do you guys think about this approach? Is there any reason not to do it like that?
Thanks.
EDIT
As pointed out by David W, enum member values are limited in length, depending on the underlying type (integer by default). So yes, I believe my method works but you are limited to characters in the ASCII table, with a maximum length of 4 or 8 characters using integers or longs respectively.
The easiest way I have found to dynamically parse a String representation of an Enumeration into the actual Enumeration type was to do the following:
Private EnumObject
[Undefined]
ValueA
ValueB
End Enum
dim enumVal as EnumObject = DirectCast([Enum].Parse(GetType(EnumObject), "ValueA"), EnumObject)
This removes the need to maintain a dictionary and allows you to just handle strings instead of converting to an Int or a Long. This does use reflection, but I have not come across any issues as long as you catch and handle any exceptions with the String Parse.
My assignment in Visual Basic 2010 is to build a order form that has two text boxes, one for the name and the other for the address.
And we're suppose to use the IndexOf method on the address.
I understand that IndexOf returns the position of a character and the number of characters.
What would be the purpose of using the IndexOf method on the address in this instance?
I don't understand what I would be searching for when the user types in it's address that's going to be numbers and string characters.
I think I understand what the IndexOf method does, somewhat, but why and what would I use it to achieve?
You'd typically use IndexOf to -
See if a string contained something
If someString.IndexOf("Avenue") > - 1 Then
'do something
End If
Get the start position of a value in a string , this could then be used to extract part of the string. e.g. someString.Substring(someString.IndexOf("#"),10) would get then next ten characters starting from where the "#" character was found in your string.
Bear in mind you'll always need to handle scenarios where IndexOf will return -1 if it does not find the string your searching for, so your code will have to handle that eventuality.
Since this is a homework question, I will answer with a question or several:
How would you normally enter a full address into a text box?
How would each part of the address be distinguishable from another?
Once you figure out how this can be done, think about IndexOf again.
having a bit of trouble finding a solution to this.
I want to take a large ordered text file of words and create - in the same order - a text file of fixed length numeric values.
For example:
Input File Output File
AAA -> 00000001
AAH -> 00002718
AAZ -> 71827651
Initially it seemed a hash function would do the trick. However they are one way. Also perhaps they are a bit "heavyweight" for this. After all, I don't need any cryptography. Plus, it's a reference file. It will never change.
Any compression is a bonus not essential. That said, I don't want the file to get any bigger than it already is. Which is why I don't just want to write out the words as text but with fixed lengths.
So, bottom line; input is a NSString of variable length, output is an integer of fixed length. And, I must be able to take the integer and figure out the string.
Any help much appreciated!
Thanks!
xj
Well, this would be a bit of a brute force method, but here's my guess.
Start by making a custom function to convert one letter of text to an integer less than 100. (I'm not sure if such a function already exists, if so then great!) You might need to just go to stuff like "if ([input isEqual: #"a"]){ return 1;}
Then, run that function on each letter of text, and get the final integer by combining the previous results.
For example:
int myVal1 = [intConverter firstLetter];
int myVal2 = [intConverter secondLetter];
int myVal3 = [intConverter thirdLetter];
int finalValue =100^3 + 100^2*myVal1 + 100*myVal2 + myVal3;
Then, finalValue would be of the form 1(myVal1)(myVal2)(myVal3), which is what I think you're looking for.
To get back the original string, simply use the mod (%) and division functions to get the individual values back, then run the intConverter function backwards. (This would probably mean writing a new function that basically runs those if statements in reverse, but oh well.)
I hope this helps.
What are the drawbacks of the String type in abap? When to use it, when not?
An example : I have a text field that should save values ranging from 0 to 12 chars, better to use a string or a Char(12)?
Thanks!
A string is stored as a dynamic array of characters while a char is statically allocated.
Some of the downsides of strings include:
Overhead - because they are dynamic the length must be stored in addition to the actual string.
The substring and offset operators don't work with strings.
Strings cannot be turned into translatable text elements.
So to answer your question, strings should only be used for fairly long values with a wide range of lengths where the additional overhead is negligible relative to the potential wasted space of a static char(x) variable.
I think CHAR is the best because you are 100% sure that the field has to only hold 0-12 characters.
string is the variable length Data type , while in char you have to define the length ..
for type C(Text field (alphanumeric characters)) and String X or hexadecimal string have initial value (X'0 … 0') .
to avoid initial value , and to use actual length C type is used
Strings are good when:
The text length will be variable.
Spaces are part of the string (trailing spaces in CHAR fields are lost)
You pass them around a lot (when STRING variable metadata is less than char field size)
You need to get the STRING length often. It is more optimal than with CHAR fields.
CHAR fields are good:
If they are small, they are fast (less than around 32 chars on unicode systems)
CHAR field literals using (') quotes instead of (`) can be made into translatable texts.
Things to remember:
All variables have metadata, but strings also has some internal pointer to the string data, which could add up to 64 bytes to memory consumption. Something to keep in mind.
When assigning a literal text to a variable, try to match the literal type to the variable type. Use 'test' for CHAR and `test` for STRING. This is usually slightly faster.
String Variable :
A String is a variable length data type which is used to store any length of data. Variable length fields are used because they save space.
String, can store any number of characters. String will allocate the memory at runtime which is also called as dynamic memory allocation, will allocate the memory as per the size of the string. Strings cannot be declared using parameters as the memory of allocation is dynamic.
But in your case, you already know max-length of field(0 - 12 characters), So CHAR type is best for use in your case. A STRING type generally used to variable length data or a long values.
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