string replace in c# [duplicate]

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Possible Duplicate:

String replace not working

I have a stirng like:

string url = "abc=$abc";
url.Replace("$abc", "123");

Then what I expected it url = "abc=123". But actually, after runing above code, the result is still is "abc=$abc", not "abc=123".

How to resolve this problem?

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You want

url = url.Replace("$abc", "123");

Replace() returns a new instance of string with the replacement operation done. It (and all other string operations) does not change the original string instance.

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Strings are immutable, this means that you create a new string instead of changing the original:

url = url.Replace("$abc", "123");

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Strings are immutable, meaning it won't change in place. Try assigning the result of replace to another string variable.

string url = "abc=$abc";
string newUrl = url.Replace("$abc", "123");

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try

url = url.Replace("$abc", "123");

String.Replace Method

Returns a new string in which all occurrences of a specified Unicode character or String in the current string are replaced with another specified Unicode character or String.

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You need to set the original string, or a new string, equal to the value returned from String.Replace. Using your example, do this:

string url = "abc=$abc";
url = url.Replace("$abc", "123");

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url = url.Replace("$abc", "123");

.Replace returns a NEW string - you must assign that back to the original string if you want to change it.

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url = url.Replace("$abc", "123");

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Replace returns a string. So you need to change your second statement to:

url = url.Replace("$abc", "123");