is there any function in vb.net to do that ??
No. However, you CAN use VB.Net to do that. All you have to do is write the
code.
Of course, first you have to analyze the problem. Programming is a
problem-solving process. Remember when you took Algebra in high school, and
they gave you word problems that you had to convert to math problems? Think
of it that way. Analysis is the process of converting a word problem to a
math (programming) problem.
I have a string
str="10*12*14"
now I want the total of this value
i.e. 10 multiply 12 multiply 14
how do i get it ?
Okay, first we start with a string. A string has no numbers in it. We want
to parse the string, as it contains text symbols that represent both data
(numbers) and process (math operators). Now, not all text is symbolic of
numbers and math operators, such as the comma for example. So, we first need
to identify what symbols of text we will use as numbers (the easy part -
0,1,2,3,4,5,6,7,8,9), and what symbols of text we will use as operators. I
cannot assume that you are only talking about multiplying numbers here. In
fact, I would guess that you may want to be able to perform all types of
arithmetical computations, IOW adding, subtracting, multiplying, and
dividing. So, for the purpose of this explanation, I'll say that our
operators are +, -, *, and /. Possibly % and \ as well.
Okay, now for the hard part. Your example is good because it contains no
spaces. We can't necessarily assume that there are spaces in the string (you
could, but I can't, since I don't know where your string will come from).
So, we need a means to parse a string into an unknown number of known single
characters, and an unknown number of combinations of 1 or more digit
characters. What is the best programmatic mechanism for doing such complex
string parsing? Offhand, I would say a Regular Expression. So, we have
solved the first part of the problem, which is how to parse the string into
a set of separate strings.
Once we have these separate strings, we must convert the numeric string
expressions to numbers, and the operators to operators, and build a purely
mathematical expression from them. Converting strings to numbers is easy,
and I don't need to explain that. Converting the operators cannot be done
directly, so we need to use selection to identify the operators, in order to
perform math on the numbers. This can be done with a Select Case Statement.
Now we need to know the rules of math, and for arithmentic they are fairly
simple. In this case, the simplicity comes in handy. We know, for example,
that (10*2*4) is equivalent to (10*2) * 4, and is equivalent to 10 * (2*4),
etc. If all we are doing is multiplying, the order of operation is not
important. But, what if we parse 10*2+4? 10*2 = 20. Add 4 and you get 24.
But 10 * (2+4) = 60. So, we're looking for a rule, and we introduce another
possible set of characters that we may need to parse, which is parentheses.
We need to identify whether we will allow the use of parentheses to change
the default rules regarding order of operation, and if so, we need to parse
parentheses, and use them in our math, not directly, but in order to perform
the operations in the correct order. Again, we're talking about selection
here. If there are no parentheses, the default order of operations applies.
If there ARE parentheses, we have to modify the order of operations, as a
program can only perform one operation at a time.
Now that we have analyzed the problem, it's a relatively straightforward
exercise to write the code. And I'll leave that to you!
--
HTH,
Kevin Spencer
Microsoft MVP
..Net Developer
What You Seek Is What You Get.
