C# String Methods IsEmpty, Find, Replace

IsEmpty, Find, Replace - Comparison C# vs MFC (CString)

IsEmpty, Find, and Replace are common used string methods in MFC (CString class).

MFC (CString) Samples:
CString somestring = L"ABCDEFG";

if (somestring.IsEmpty())
    // somestring is empty

if (somestring.Find(L"ABC")!=-1)
    // found "ABC" in somestring

// somestring == L"abcDEFG"


In C# we use string.IsNullOrEmpty instead of IsEmpty and IndexOf instead of Find:

MFC (CString) C# (string)
somestring.IsEmpty() string.IsNullOrEmpty(somestring)
somestring.Find (str) somestring.IndexOf(str)
somestring.Replace (strold,strnew) somestring = somestring.Replace(strold,strnew)


See also: Comparison of string operations: Left, Mid, Right - C# vs MFC



Check for an Empty String: IsNullOrEmpty in C#

Checks if a string is Null or Empty:

// Sample: Check if somestring is empty
string somestring = string.Empty;
if (string.IsNullOrEmpty(somestring))
    // somestring is empty

Don't use comparisons like:
if (somestring.Length==0) ... or
if (somestring=="") ...
The comparison will result in an exception(!) if somestring == string.Empty or somestring == Null (no object available)


Search in a String: IndexOf in C#

Search for a string inside a string and return the index ( index==-1 if string not found)

// Sample: Search for "DEF" inside "ABCDEFG"
string somestring = "ABCDEFG";
int index = somestring.IndexOf("DEF");
// index == 3 (starts by 0)

if (index == -1)
    // not found


Replace String in C#

Replace a string inside a string:

// Sample: Replace "ABC" with "abc" inside "ABCDEFG"
string somestring = "ABCDEFG";
somestring = somestring.Replace("ABC","abc");
// somestring == "abcDEFG"

"Replace" returns a new string ... it does not change the "old" string, so you need to use: "somestring = somestring.Replace(...)"

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