using System;
using System.IO;
namespace Test_Arrays_and_Files
{
class Program
{
static void Main(string[] args)
{
string tFile = #"C:\Programming\GLO\DC\dcw.txt";
string read = File.ReadAllText(tFile);
string[] test = read.Split(',');
int[] ints = Array.ConvertAll(test, int.Parse);
Console.WriteLine(ints[0]);
}
}
}
Input Data:
Text File Contents:(1 value per line,)
35,
35,
40,
40,
40,
getting System.FormatException: Input string was not in correct format
please help and sorry for bad post I'm new here
There are two issues in your code,
Your string is ending with , which is creating empty record after the split. This is the reason you are getting the error.
Your delimiter could be $",{Environment.NewLine}" not only ','.
So to convert given string to int array, first Trim() the input string by , and then split by $",{Environment.NewLine}".
Like,
using System.Linq;
...
var result = str.Trim(',') //Remove leading and trailing comma(s), You can use `TrimEnd()` as well
.Split($",{Environment.NewLine}", StringSplitOptions.RemoveEmptyEntries) //Split by given delimiter.
.Select(int.Parse)
.ToArray(); //Convert string[] to int[]
Try online
You're only getting it because the file has a comma at the end, which means Split ends up churning out an empty string in the very last position. int.Parse will choke on the empty string
Plenty of ways you could solve it, one is to tell Split not to return you empties, by changing the split line of your code to:
string[] test = read.Split(new[]{','}, StringSplitOptions.RemoveEmptyEntries);
You could instead trim the comma off the end, but using the above approach would mean your parsing would survive a blank line in the middle of the file too so overall it's more robust
Generally when parsing strings it's more robust to use TryParse than Parse. TryParse takes in the number variable to set the result to and returns you a Boolean telling if the parsing succeeded
int[] ints = Array.ConvertAll(test, GetIntOrMinusOne);
//put a method helper
private int GetIntOrMinusOne(string s){
if(int.TryParse(s, out var t)
return t;
return -1;
}
For this we need to get a bit more involved with the ConvertAll call. Instead of telling ConvertAll to call a "method that converts a string to an int" like int.Parse, we need to write our own mini method that tries to parse and if it fails return something like -1, then nominate that as the method to call to do the conversion, not int.Parse
It's important to note that this would introduce -1 into the resulting int[] array wherever there was bad data in the string array.. In your later processing you would then do some check to avoid them (such as skipping them)
You can shorten that code above by turning the method into a lambda:
int[] ints = Array.ConvertAll(test, s => int.TryParse(s, out var t) ? t : -1);
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
a lambda; "just the important parts of a method"
But I'm not sure that you'll have come across lambdas yet, judging by the style of the rest of the code
Related
I am writing program to add numbers from string which will be seperated from delimeters
private static readonly char[] Separators = { ',', '\n', '/','#' };
public int Add(string numbers)
{
if (numbers.Equals(string.Empty))
{
return 0;
}
return numbers.Split(Separators).Select(int.Parse).Sum();
}
When i pass the following string to Add method //#\n2#3
Then i get below error Input string was not in a correct format.
I expect answer to be 5
By default, string.Split will create empty groups if two delimiters are right next to each other. For example "3,,4".Split(','); will produce an array with three elements ("3", empty string, and "4").
You can change this in one of two ways. The first (and probably simpler) is to have the Split ignore empty entries.
numbers.Split(Separators, StringSplitOptions.RemoveEmptyEntries)
Or you can use Where in Linq
numbers.Split(Separators).Where(x => x.Length > 0)
This will prevent elements with a blank string value reaching int.Parse. Of course, there are still other things you should do to validate your input before attempting to parse, but that's another topic.
Basically, I am trying to convert what appears to be an array of integer values stored in a string type.
[123,234,345,456] // example
Currently, I am doing the following to convert string to List<int> or an int[]:
var intList = "[123,234,345,456]".Replace("[","").Replace("]","").Split(new[] {','}, StringSplitOptions.RemoveEmptyEntries).Select(int.Parse).Tolist();
Perform required operations (sort, add, remove) on the list and convert it back to a string:
string.Format("[{0}]", string.Join(",", intList));
But then this got me thinking. The data that I am working with looks like JSON. Surely there must a more direct way of converting the string into an array of integers?
I looked at using JArray.Parse(string) from Newtonsoft.Json.Linq but isn't that just adding an extra layer of complexity as now I am dealing with JArray<JToken> instead of standard int[].
If anyone has a neater solution that doesn't involve adding methods, extensions or libraries I would appreciate if you can share your knowledge.
You are correct - JSON can do this for you:
using System;
using Newtonsoft.Json;
namespace Demo
{
class Program
{
static void Main()
{
string test = "[123,234,345,456]";
var result = JsonConvert.DeserializeObject<int[]>(test);
// This prints "123, 234, 345, 456"
Console.WriteLine(string.Join(", ", result));
string andBackAgain = JsonConvert.SerializeObject(result);
// This prints "[123,234,345,456]"
Console.WriteLine(andBackAgain);
}
}
}
If your intention is to parse numbers with double quotes then
string input = #"[123,234,345,456]";
string pattern = #"\d+";
var result = Regex.Replace(input, pattern, "\"$&\"");
result.Dump();
//["123","234","345","456"]
or to parse whole object inside array braces
string input = #"[123,234,345,456]";
string pattern = #"(\d+\s*,?\s*)+";
var result = Regex.Replace(input, pattern, "\"$&\"");
result.Dump();
//["123,234,345,456"]
string aresultlist = File.ReadAllLines(data).ToString();
var bresultlist = aresultlist.Split().Select(s => Convert.ToInt32(s));
List<int> resultlist = bresultlist.ToList();
Can anyone help with the FormatException I keep getting on this block, "It's the datetime Format, take date first exception". It's a string read from a space delimited text file.
Try this:
List<int> resultList = File
.ReadLines(data) // you've got IEnumerable<string>
.Select(line => line.Split()) // -/- IEnumerable<string[]>
.Select(ietms => int.Parse(items[0])) // -/- IEnumerable<int>
.ToList(); // finally, it's List<int>
I've assumed that it's the 1st item of the line which should be converted into int: int.Parse(items[0]), change 0 into the right index if required.
Try avoiding ReadAllLines in favor to ReadLines: you don't what all the file (which can be long) to be read into an array in one go
the problem is that ReadAllLines returns a string[]. If you call ToString on such an object you get the namespace.classname as a string. So in your case:
System.String[]
splitting this string results definetely not a number. But in a string[] with on entry, namely:
System.String[]
If your file has only one line with the space delimited numbers, I would suggest to use File.ReadAllText. It will read the entire content of the file and return it as 1 string. This way you can use your code almost as it is.
string aresultlist = File.ReadAllText(data);
var bresultlist = aresultlist.Split().Select(s => Convert.ToInt32(s));
List<int> resultlist = bresultlist.ToList();
EDIT:
As suggested by Gilad Green you might have content in the file that cannot be parsed to a number and will throw an exception. To avoid this you can follow this example
I am trying to parse a string into array and find a very concise approach.
string line = "[1, 2, 3]";
string[] input = line.Substring(1, line.Length - 2).Split();
int[] num = input.Skip(2)
.Select(y => int.Parse(y))
.ToArray();
I tried remove Skip(2) and I cannot get the array because of non-int string. My question is that what is the execution order of those LINQ function. How many times is Skip called here?
Thanks in advance.
The order is the order that you specify. So input.Skip(2) skips the first two strings in the array, so only the last remains which is 3. That can be parsed to an int. If you remove the Skip(2) you are trying to parse all of them. That doesn't work because the commas are still there. You have splitted by white-spaces but not removed the commas.
You could use line.Trim('[', ']').Split(','); and int.TryParse:
string line = "[1, 2, 3]";
string[] input = line.Trim('[', ']').Split(',');
int i = 0;
int[] num = input.Where(s => int.TryParse(s, out i)) // you could use s.Trim but the spaces don't hurt
.Select(s => i)
.ToArray();
Just to clarify, i have used int.TryParse only to make sure that you don't get an exception if the input contains invalid data. It doesn't fix anything. It would also work with int.Parse.
Update: as has been proved by Eric Lippert in the comment section using int.TryParse in a LINQ query can be harmful. So it's better to use a helper method that encapsulates int.TryParse and returns a Nullable<int>. So an extension like this:
public static int? TryGetInt32(this string item)
{
int i;
bool success = int.TryParse(item, out i);
return success ? (int?)i : (int?)null;
}
Now you can use it in a LINQ query in this way:
string line = "[1, 2, 3]";
string[] input = line.Trim('[', ']').Split(',');
int[] num = input.Select(s => s.TryGetInt32())
.Where(n => n.HasValue)
.Select(n=> n.Value)
.ToArray();
The reason it does not work unless you skip the first two lines is that these lines have commas after ints. Your input looks like this:
"1," "2," "3"
Only the last entry can be parsed as an int; the initial two will produce an exception.
Passing comma and space as separators to Split will fix the problem:
string[] input = line
.Substring(1, line.Length - 2)
.Split(new[] {',', ' '}, StringSplitOptions.RemoveEmptyEntries);
Note the use of StringSplitOptions.RemoveEmptyEntries to remove empty strings caused by both comma and space being used between entries.
I think it would be better you do it this way:
JsonConvert.DeserializeObject(line, typeof(List<int>));
you might try
string line = "[1,2,3]";
IEnumerable<int> intValues = from i in line.Split(',')
select Convert.ToInt32(i.Trim('[', ' ', ']'));
I have a numeric string like this 2223,00. I would like to transform it to 2223. This is: without the information after the ",". Assume that there will be only two decimals after the ",".
I did:
str = str.Remove(str.Length - 3, 3);
Is there a more elegant solution? Maybe using another function? -I don´t like putting explicit numbers-
You can actually just use the Remove overload that takes one parameter:
str = str.Remove(str.Length - 3);
However, if you're trying to avoid hard coding the length, you can use:
str = str.Remove(str.IndexOf(','));
Perhaps this:
str = str.Split(",").First();
This will return to you a string excluding everything after the comma
str = str.Substring(0, str.IndexOf(','));
Of course, this assumes your string actually has a comma with decimals. The above code will fail if it doesn't. You'd want to do more checks:
commaPos = str.IndexOf(',');
if(commaPos != -1)
str = str.Substring(0, commaPos)
I'm assuming you're working with a string to begin with. Ideally, if you're working with a number to begin with, like a float or double, you could just cast it to an int, then do myInt.ToString() like:
myInt = (int)double.Parse(myString)
This parses the double using the current culture (here in the US, we use . for decimal points). However, this again assumes that your input string is can be parsed.
String.Format("{0:0}", 123.4567); // "123"
If your initial value is a decimal into a string, you will need to convert
String.Format("{0:0}", double.Parse("3.5", CultureInfo.InvariantCulture)) //3.5
In this example, I choose Invariant culture but you could use the one you want.
I prefer using the Formatting function because you never know if the decimal may contain 2 or 3 leading number in the future.
Edit: You can also use Truncate to remove all after the , or .
Console.WriteLine(Decimal.Truncate(Convert.ToDecimal("3,5")));
Use:
public static class StringExtensions
{
/// <summary>
/// Cut End. "12".SubstringFromEnd(1) -> "1"
/// </summary>
public static string SubstringFromEnd(this string value, int startindex)
{
if (string.IsNullOrEmpty(value)) return value;
return value.Substring(0, value.Length - startindex);
}
}
I prefer an extension method here for two reasons:
I can chain it with Substring.
Example: f1.Substring(directorypathLength).SubstringFromEnd(1)
Speed.
You could use LastIndexOf and Substring combined to get all characters to the left of the last index of the comma within the sting.
string var = var.Substring(0, var.LastIndexOf(','));
You can use TrimEnd. It's efficient as well and looks clean.
"Name,".TrimEnd(',');
Try the following. It worked for me:
str = str.Split(',').Last();
Since C# 8.0 it has been possible to do this with a range operator.
string textValue = "2223,00";
textValue = textValue[0..^3];
Console.WriteLine(textValue);
This would output the string 2223.
The 0 says that it should start from the zeroth position in the string
The .. says that it should take the range between the operands on either side
The ^ says that it should take the operand relative to the end of the sequence
The 3 says that it should end from the third position in the string
Use lastIndexOf. Like:
string var = var.lastIndexOf(',');