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I am working on a little project, that at a certain point need to convert a string to int.
I tried the following things:
//first try
value1 = int.TryParse(value[0].tostring(), out i)
//second
value1 = Convert.ToInt32(value[0].tostring())
//third
value1 = int.Parse(value[0].tostring())
I even wrote my own conversion method because I was at a loss.
The values I am trying to convert are queried from a MySQL database.
Thank for your help
EDIT:
I know tryparse should have 2 params.
And the error iam getting is a formatexception
Input string was not in a correct format.
I got that on all the tries.
the value in my test case is 2500
Keep in mind that that number is received from a db
I tried the above snippets while using a hard coded value. And that works fine.
EDIT 2:
//http://imgur.com/NSyg2rJ
One:
The signature of int.TryParse() is incorrect:
int result = 0;
bool parsedSuccessfully = Int32.TryParse(value[0].ToString(), out result);
//If successful, result will hold the value.
Two:
The signature of Convert.ToInt32() is correct, minus the case of the .ToString() method. This is failing because value or value[0] is null, or it cannot convert something like the string "NotAnInt" to an int.
Three:
The signature of int.Parse() is correct, but is failing for the same reasons as two.
Try this -
int value1;
if (Int.TryParse(value[0].ToString(), out value1))
{
//conversion successful
}
Related
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So I made a simple c# file reader because I was bored and added an if statement to filter the results. But when I ran it, it gave me more results than I wanted. I was supposed to get
276, 2, and there was only one line inside the file with that value, but I got multiple. I checked the file and it had lines ending with the same value. I tried string.Equals(line, "276, 2") but it gave me the same results. I doubt there isn't something in c# that doesn't solve this issue.
You can use Regex, as it's mentioned in this issue
bool result = Regex.IsMatch(line, "\\b276, 2\\b");
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I am enrolled in a beginner C# online course.
Learning about how to deal with coding errors is mostly for the student to resolve.
Visual Studio 2019 is the preferred course IDE.
Some VS error messages are easy while others are very tricky to understand and resolve.
I am working on an assessable item - so not posting the full program code here.
A key section of code is throwing error CS1501 - I have searched internet for solution though do not understand how those maters fit with my situation.
Key code section as follows:
int abc;
abc = Console.ReadLine(Convert.ToInt32());
Curly red lines in VS are under 'ToInt32' with error notes: int
Convert.ToInt32(bool value) (18+ overloads) CS1501 No overload
for method 'ToInt32' takes 0 arguments.
Thanks.
You have it the wrong way around
int abc;
abc = Convert.ToInt32(Console.ReadLine());
The long story
Console.ReadLine() returns a string
Convert.ToInt32 takes an input (of varying type) to return an int
If you look at all the overloads for Convert.ToInt32 you will soon notice there are no variants that take 0 arguments. Which is what the compiler is telling you.
No overload for method 'ToInt32' takes 0 arguments.
However, never use Convert.ToInt32 to parse user input
Use int.TryParse instead
Converts the string representation of a number to its 32-bit signed
integer equivalent. A return value indicates whether the operation
succeeded.
int abc;
var input = Console.ReadLine();
if(!int.TryParse(input, out abc))
// user couldn't type a number, do something else instead
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The static Matches is
public static void Matches(string expectedRegexPattern, string actualString);
What is the difference between when I pass expectedRegexPattern value instead of actualString value and passing actualString value instead of expectedRegexPattern value?
Way 1 - Assert.Matches("EN", result[0].LanguageCode);
Way 2 - Assert.Matches(result[0].LanguageCode,"EN");
Both of ways doing same work with same performance. So am confused about the difference between the above ways and which one is best?
#Stivi correctly points out a significant difference in the case of Matches, but there's another less significant but still important distinction even for Equals and other assertion methods.
You might get an incorrect message in the test log output. Many testing frameworks will log an error such as
Values do not match: expected: {expectedValue}, actual: {actualValue}".
So if you switched them, you'd see the wrong "expected" value, potentially confusing someone trying to diagnose a problem.
Take this test as an example:
void TestValueIsZero():
{
int value = 1;
Assert.Equals(0, value);
// logs "Values to not match. expected: 0, actual: 1
Assert.Equals(value, 0);
// logs "Values to not match. expected: 1, actual: 0
}
Someone looking at the failed test logs might be confused by the incorrect "expected" and "actual" values in the log due to the switched parameters.
The mechanics may be exactly the same regardless of the order of parameters (compare the two objects and return true if no differences are found), but the semantics are still important.
I expect that you are using xunit as test framework because i have found that method there. So if you only want to check if both strings have the same content you could also use Assert.Equal("Your text", "Your text"). The Assert.Matches method is used to validate if your text is in a desired format. The format is described by .net regular expressions. For example with this call Assert.Matches("^[0-9]$", "1") you can check if your string is a number between 0 and 9. If you change the order of the parameters to Assert.Matches( "1", "^[0-9]$") the method will throw an exception and your test will be marked as failed.
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My program has been receiving this error recently and I am not sure why. The code that is triggering it is:
foreach (var lot in item.LotNum.Split('|'))
{
string vendor = string.Empty;
if (lot.Trim().Contains("-"))
vendor = lot.Trim().Substring(0, item.LotNum.IndexOf("-"));
}
LotNum = "br549 | BR549 | 570-PRIOR" and lot is "570-PRIOR" (without quotes) when the error triggers. I've not used IndexOf before and so I am not sure what is wrong with the string that is being sent in. I want to check for what causes the error beforehand because the exception is stopping the program and the bad data will be there for a while until it is fixed, and more may be added in the future.
Any help would be appreciated!
New answer according your code update:
var lots = item.LotNum.Split('|');
foreach (var lot in lots)
{
string vendor = string.Empty;
if (lot.Contains("-"))
vendor = lot.Substring(0, lot.IndexOf("-")).Trim();
}
Again, you were using IndexOf for a variable different than the one you want to get a substring
You are using IndexOf for a variable different than the one you want to get a substring, so, the index will be out of range.
Try with: edited
variable = variable.Trim();
int index = variable.IndexOf("-");
if (index > 0)
variable.Substring(0, index);
Another way to do this is to check for the existence of the character using Contains, and if it's found use the IndexOf, otherwise just use the Length of the string (and put Trim at the end to avoid issues with using the Length after trimming):
variable.Substring(0, variable.Contains('-')
? variable.IndexOf('-')
: variable.Length)
.Trim();
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The application that I've made I've got a text box called service cost. This allows the user to enter the cost of the service they have provided and this is decimal. I'm trying to get this service cost displayed in a DGV, I've got everything else working apart from this.
currentComputer.ServiceCost = Convert.ToDecimal(txtServiceCost);
The above is the code that I currently have, is there something wrong that I've done here?
From the question it is clear that txtServiceCost is the TextBox, and Convert.ToDecimal() expects a string as input so you should use txtServiceCost.Text instead for txtServiceCost. Since txtServiceCost is a control where as txtServiceCost.Text is a string
currentComputer.ServiceCost = Convert.ToDecimal(txtServiceCost.Text);
But i would like to suggest you to use decimal.TryParse
decimal userInput;
if (!decimal.TryParse(txtServiceCost.Text, out userInput))
{
// Throw some warning here that invalid input
}
currentComputer.ServiceCost = userInput;