C# testing to see if a string is an integer?
C#.NetStringIntegerC# Problem Overview
I'm just curious as to whether there is something built into either the C# language or the .NET Framework that tests to see if something is an integer
if (x is an int)
// Do something
It seems to me that there might be, but I am only a first-year programming student, so I don't know.
C# Solutions
Solution 1 - C#
Use the int.TryParse method.
string x = "42";
if(int.TryParse(x, out int value))
// Do something
If it successfully parses it will return true, and the out result will have its value as an integer.
Solution 2 - C#
If you just want to check type of passed variable, you could probably use:
var a = 2;
if (a is int)
{
//is integer
}
//or:
if (a.GetType() == typeof(int))
{
//is integer
}
Solution 3 - C#
I think that I remember looking at a performance comparison between int.TryParse and int.Parse Regex and char.IsNumber and char.IsNumber was fastest. At any rate, whatever the performance, here's one more way to do it.
bool isNumeric = true;
foreach (char c in "12345")
{
if (!Char.IsNumber(c))
{
isNumeric = false;
break;
}
}
Solution 4 - C#
For Wil P solution (see above) you can also use LINQ.
var x = "12345";
var isNumeric = !string.IsNullOrEmpty(x) && x.All(Char.IsDigit);
Solution 5 - C#
its simple... use this piece of code
bool anyname = your_string_Name.All(char.IsDigit);
it will return true if your string have integer other wise false...
Solution 6 - C#
If you only want to check whether it's a string or not, you can place the "out int" keywords directly inside a method call. According to dotnetperls.com website, older versions of C# do not allow this syntax. By doing this, you can reduce the line count of the program.
string x = "text or int";
if (int.TryParse(x, out int output))
{
// Console.WriteLine(x);
// x is an int
// Do something
}
else
{
// x is not an int
}
If you also want to get the int values, you can write like this.
Method 1
string x = "text or int";
int value = 0;
if(int.TryParse(x, out value))
{
// x is an int
// Do something
}
else
{
// x is not an int
}
Method 2
string x = "text or int";
int num = Convert.ToInt32(x);
Console.WriteLine(num);
Referece: https://www.dotnetperls.com/parse
Solution 7 - C#
This function will tell you if your string contains ONLY the characters 0123456789.
private bool IsInt(string sVal)
{
foreach (char c in sVal)
{
int iN = (int)c;
if ((iN > 57) || (iN < 48))
return false;
}
return true;
}
This is different from int.TryParse() which will tell you if your string COULD BE an integer.
eg. " 123\r\n" will return TRUE from int.TryParse() but FALSE from the above function.
...Just depends on the question you need to answer.
Solution 8 - C#
private bool isNumber(object p_Value)
{
try
{
if (int.Parse(p_Value.ToString()).GetType().Equals(typeof(int)))
return true;
else
return false;
}
catch (Exception ex)
{
return false;
}
}
Something I wrote a while back. Some good examples above but just my 2 cents worth.
Solution 9 - C#
Maybe this can be another solution
try
{
Console.Write("write your number : ");
Console.WriteLine("Your number is : " + int.Parse(Console.ReadLine()));
}
catch (Exception x)
{
Console.WriteLine(x.Message);
}
Console.ReadLine();
Solution 10 - C#
I've been coding for about 2 weeks and created a simple logic to validate an integer has been accepted.
Console.WriteLine("How many numbers do you want to enter?"); // request a number
string input = Console.ReadLine(); // set the input as a string variable
int numberTotal; // declare an int variable
if (!int.TryParse(input, out numberTotal)) // process if input was an invalid number
{
while (numberTotal < 1) // numberTotal is set to 0 by default if no number is entered
{
Console.WriteLine(input + " is an invalid number."); // error message
int.TryParse(Console.ReadLine(), out numberTotal); // allows the user to input another value
}
} // this loop will repeat until numberTotal has an int set to 1 or above
you could also use the above in a FOR loop if you prefer by not declaring an action as the third parameter of the loop, such as
Console.WriteLine("How many numbers do you want to enter?");
string input2 = Console.ReadLine();
if (!int.TryParse(input2, out numberTotal2))
{
for (int numberTotal2 = 0; numberTotal2 < 1;)
{
Console.WriteLine(input2 + " is an invalid number.");
int.TryParse(Console.ReadLine(), out numberTotal2);
}
}
if you don't want a loop, simply remove the entire loop brace
Solution 11 - C#
It is possible to try this as well:
var ix=Convert.ToInt32(x);
if (x==ix) //if this condition is met, then x is integer
{
//your code here
}