如何将string.empty替换为“ 0”

Question

Just like the title says.

I've tried doing str.Replace("","0"); but it gave me error because oldValue has zero length.

Is it possible to replace string.Empty into something?

Edit:

I am maintaining a program and I encountered that the program was calling a method that'll return a string then be converted to Int32.

int x = Convert.toInt32(Method1());

public string Method1()
{
      string retString = string.Empty;
      //Do Something
      return retString
}

Answer 1

String.Replace takes two string arguments oldValue and newValue. You specified the newValue 0 however an empty string is not legal for the oldValue.

try below code :-

str.Replace(" ","0"); 

or you can just assign "0" to emptry string as below :-

if(str == string.Empty)
{
   str = "0";
}

or making it simple :-

String.IsNullOrWhiteSpace(str) ? "0" : str;

Answer 2

You can't replace empty string within the string, but you can replace, say, spaces , eg

  str = str.Replace(" ", "0"); // providing str is not null

Or you can substitute empty string with "0" :

  if (String.IsNullOrEmpty(str))
    str = "0";

When parsing string into int you can do something like that:

  int x = String.IsNullOrEmpty(str) ? 0 : Convert.ToInt32(str);

Answer 3

在method（）中，您可以执行以下操作：

return String.IsNullOrEmpty(retString) ? "0" : retString;

Answer 4

您可以使用此单行代码简单地为空，零长度或空格字符串返回"0" ：

return String.IsNullOrWhiteSpace(str) ? "0" : str;

Answer 5

如果要检查该值是否为空，然后将该值设置为零，否则使用默认值，可以使用内联，如下所示：

return string.IsNullOrWhiteSpace(retString ) ? "0" : retString;

Answer 6

如果知道str为空，则可以使用star =“ a”。如果要检查，请在if条件中编写语句。

Answer 7

After your edit:

To convert an empty string to 0 , and parse a non-empty string as an integer, I wouldn't deal with a "0" at all, but combine the two in a single method. For example:

int Parse(string s, int d = 0) {
  if (string.IsNullOrEmpty(s))
    return d;

  return int.Parse(s);
}

Answer 8

Try This...

public string Method1()
{
      string retString = string.Empty;
      //Do Something
      return string.IsNullOrEmpty(retString)?"0":retString;
}

Answer 9

It is not possible to replace string.Empty by "0". It will throw ArgumentException.

    An unhandled exception of type 'System.ArgumentException' occurred in mscorlib.dll.
Additional information: String cannot be of zero length.

You can try following code:

if(retString == string.Empty)
{
retString = "0";
}

Answer 10

It sounds like your best option would be int.TryParse , if you encounter a string that can't be set to a valid value, it will set it to the default value for an integer (0) as well as returning a boolean so you can know this has happened.

int myInt;
if(!int.TryParse(myStringVariable, out myInt))
{
    //Invalid integer you can put something here if you like but not needed
    //myInt has been set to zero
}

//The same code without the if statement, still sets myInt
int.TryParse(myStringVariable, out myInt);