How can I check if a string is a number

Question

I d like to know on C  how to check if a string is a number  and just a number    Example    141241   Yes 232a23   No 12412a   No   and so on     Is there a specific function

User · Answer

If you want to validate if each character is a digit and also return the character that is not a digit as part of the error message validation  then you can loop through each char   string num    123x    foreach  char c in num ToArray          if   Char IsDigit c                 Console WriteLine  character     c     is not a number            return

User · Answer

public static void Main                         string id    141241               string id1    232a23               string id2    12412a                validation  id   id1   id2                     public static void validation params object   list                        string s                   int result              string  Msg                    for  int i   0  i  lt  list Length  i                                  s    list i  ToString                     if  string IsNullOrEmpty s                                        Msg    Please Enter the value                                     if  int TryParse s  out result                                        Msg    Enter      s ToString        value is Integer                                    else                                      Msg    This is not Integer value

User · Answer

namespace Exception       class Program               static void Main string   args                        bool isNumeric              int n              do                               Console Write  Enter a number                     isNumeric   int TryParse Console ReadLine    out n                 while  isNumeric    false               Console WriteLine  Thanks for entering number    n               Console Read

User · Answer

int result   0  bool isValidInt   int TryParse  1234   out result     isValidInt should be true   result is the integer 1234   Of course  you can check against other number types  like decimal or double

User · Answer

Perhaps you re looking for the int TryParse function   http   msdn microsoft com en-us library system int32 tryparse aspx

User · Answer

You should use the TryParse method for the int  string text1    x       int num1      bool res   int TryParse text1  out num1       if  res    false                   String is not a number

User · Answer

int num  bool isNumeric   int TryParse  123   out num

User · Answer

use this       double num      string candidate    1       if  double TryParse candidate  out num                    It s a number

User · Answer

string str    123   int i   Int Parse str     If str is a valid integer string then it will be converted to integer and stored in i other wise Exception occur

User · Answer

Use int TryParse     string input    141241   int ouput  bool result   int TryParse input  out output     result will be true if it was

User · Answer

The problem with some of the suggested solutions is that they don t take into account various float number formats  The following function does it   public bool IsNumber String value        double d      if  string IsNullOrWhiteSpace value            return false       else                 return double TryParse value Trim    System Globalization NumberStyles Any                              System Globalization CultureInfo InvariantCulture  out d       It assumes that the various float number styles such es decimal point  English  and decima comma  German  are all allowed  If that is not the case  change the number styles paramater  Note that Any does not include hex mumbers  because the type double does not support it

User · Answer

This is my personal favorite  private static bool IsItOnlyNumbers string searchString    return  String IsNullOrEmpty searchString   amp  amp  searchString All char IsDigit

User · Answer

Use Int32 TryParse    int num   bool isNum   Int32 TryParse   string to test    out num    if  isNum          Is a Number   else         Not a number     MSDN Reference

User · Answer

Try This  here i perform addition of no and concatenation of string   private void button1 Click object sender  EventArgs e                        bool chk chk1              int chkq              chk   int TryParse textBox1 Text  out chkq               chk1   int TryParse textBox2 Text  out chkq               if  chk1  amp  amp  chk                                double a   Convert ToDouble textBox1 Text                   double b   Convert ToDouble textBox2 Text                   double c   a   b                  textBox3 Text   Convert ToString c                             else                               string f  d s                  f   textBox1 Text                  d   textBox2 Text                  s   f   d                  textBox3 Text   s

User · Answer

Look up double TryParse   if you re talking about numbers like 1  -2 and 3 14159  Some others are suggesting int TryParse    but that will fail on decimals  string candidate    quot 3 14159 quot   if  double TryParse candidate  out var parsedNumber            parsedNumber is a valid number      EDIT  As Lukasz points out below  we should be mindful of the thread culture when parsing numbers with a decimal separator  i e  do this to be safe  double TryParse candidate  NumberStyles AllowDecimalPoint  CultureInfo InvariantCulture  out var parsedNumber

User · Answer

int TryPasrse   Methode is the best way so if the value was string you will never have an exception   instead of the TryParse Methode return to you bool value so you will know if the parse operation succeeded or failed  string yourText    2   int num  bool res   int TryParse yourText  out num   if  res    true           the operation succeeded and you got the number in num parameter   else         the operation failed

User · Answer

int value  if  int TryParse  your string   out value         Console WriteLine value

User · Answer

Yes there is  int temp  int TryParse  141241   out temp    true int TryParse  232a23   out temp    false int TryParse  12412a   out temp    false   Hope this helps

User · Answer

I m not a programmer of particularly high skills  but when I needed to solve this  I chose what is probably a very non-elegant solution  but it suits my needs       private bool IsValidNumber string  checkString  string  checkType                float  checkF          int  checkI          bool  result   false           switch   checkType                        case  int                    result   int TryParse  checkString  out  checkI                   break              case  float                    result   Single TryParse  checkString  out  checkF                   break                    return  result           I simply call this with something like   if  IsValidNumber  1 2    float    etc      It means that I can get a simple true false answer back during If    Then comparisons  and that was the important factor for me  If I need to check for other types  then I add a variable  and a case statement as required

User · Answer

If you just want to check if a string is all digits  without being within a particular number range  you can use   string test    123   bool allDigits   test All char IsDigit

User · Answer

Many datatypes have a TryParse-method that will return true if it managed to successfully convert to that specific type  with the parsed value as an out-parameter   In your case these might be of interest   http   msdn microsoft com en-us library system int32 tryparse aspx  http   msdn microsoft com en-us library system decimal tryparse aspx

User · Answer

Yep - you can use the Visual Basic one in C  It s all  NET  the VB functions IsNumeric  IsDate  etc are actually static methods of the Information class  So here s your code   using Microsoft VisualBasic      Information IsNumeric  object

User · Answer

Starting with C  7 0  you can declare the out variable in the argument   list of the method call  rather than in a separate variable   declaration  This produces more compact  readable code  and also   prevents you from inadvertently assigning a value to the variable   before the method call    bool isDouble   double TryParse yourString  out double result     https   docs microsoft com en-us dotnet csharp language-reference keywords out-parameter-modifier

User · Answer

You could use something like the following code       string numbers    numbers you want to check        Regex regex   new Regex    0-9             if  regex IsMatch numbers                   string value is a number

User · Answer

Regex IsMatch stringToBeChecked      d      Regex IsMatch  141241       d         True  Regex IsMatch  232a23       d         False  Regex IsMatch  12412a       d         False

[c#] How can I check if a string is a number?

Examples related to c#