C testing to see if a string is an integer

Question

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

User · Answer

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.

User · Answer

Use the int TryParse method   string x    42   int value  if int TryParse x  out value        Do something   If it successfully parses it will return true  and the out result will have its value as an integer

User · Answer

For Wil P solution  see above  you can also use LINQ   var x    12345   var isNumeric    string IsNullOrEmpty x   amp  amp  x All Char IsDigit

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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   lt  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  lt  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

User · Answer

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

[c#] C# testing to see if a string is an integer?

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