How to change 1 char in the string

Question

I have this code   string str    valta is the best place in the World     I need to replace the first symbol   When I try this   str 0     M     I received an error  How can I do this

User · Accepted Answer

Strings are immutable  meaning you can t change a character  Instead  you create new strings   What you are asking can be done several ways  The most appropriate solution will vary depending on the nature of the changes you are making to the original string  Are you changing only one character  Do you need to insert delete append   Here are a couple ways to create a new string from an existing string  but having a different first character   str    M    str Remove 0  1    str    M    str Substring 1     Above  the new string is assigned to the original variable  str   I d like to add that the answers from others demonstrating StringBuilder are also very appropriate  I wouldn t instantiate a StringBuilder to change one character  but if many changes are needed StringBuilder is a better solution than my examples which create a temporary new string in the process  StringBuilder provides a mutable object that allows many changes and or append operations  Once you are done making changes  an immutable string is created from the StringBuilder with the  ToString   method  You can continue to make changes on the StringBuilder object and create more new strings  as needed  using  ToString

User · Answer

I made a Method to do this      string test    Paul       test   ReplaceAtIndex 0   M   test                   static string ReplaceAtIndex int i  char value  string word                char   letters   word ToCharArray            letters i    value          return string Join     letters

User · Answer

I usually approach it like this     char   c   text ToCharArray       for  i 0  i lt c Length  i             if  c i  gt  9     c i  lt  0      use any rules of your choice            c i          put in any character you like                  the new string can have the same name  or a new variable           String text new string c

User · Answer

I suggest you to use StringBuilder class for it and than parse it to string if you need   System Text StringBuilder strBuilder   new System Text StringBuilder  valta is the best place in the World    strBuilder 0     M   string str strBuilder ToString      You can t change string s characters in this way  because in C  string isn t dynamic and is immutable and it s chars are readonly  For make sure in it try to use methods of string  for example  if you do str ToLower   it makes new string and your previous string doesn t change

User · Answer

Merged Chuck Norris s answer w  Paulo Mendon  a s using extensions methods        lt summary gt      Replace a string char at index with another char      lt  summary gt       lt param name  text  gt string to be replaced lt  param gt       lt param name  index  gt position of the char to be replaced lt  param gt       lt param name  c  gt replacement char lt  param gt  public static string ReplaceAtIndex this string text  int index  char c        var stringBuilder   new StringBuilder text       stringBuilder index    c      return stringBuilder ToString

User · Answer

Strings are immutable  You can use the string builder class to help    string str    valta is the best place in the World    StringBuilder strB   new StringBuilder str    strB 0     M

User · Answer

While it does not answer the OP s question precisely  depending on what you re doing it might be a good solution   Below is going to solve my problem   Let s say that you have to do a lot of individual manipulation of various characters in a string   Instead of using a string the whole time use a char   array while you re doing the manipulation   Because you can do this    char   array    valta is the best place in the World  ToCharArray      Then manipulate to your hearts content as much as you need      array 0     M     Then convert it to a string once you re done and need to use it as a string   string str   new string array

User · Answer

str    M    str Substring 1     If you ll do several such changes use a StringBuilder or a char      The threshold of when StringBuilder becomes quicker is after about 5 concatenations or substrings  but note that grouped concatenations of a    b    c   d    e    f are done in a single call and compile-type concatenations of  a     b     c  don t require a call at all    It may seem that having to do this is horribly inefficient  but the fact that strings can t be changes allows for lots of efficiency gains and other advantages such as mentioned at Why  NET String is immutable

[c#] How to change 1 char in the string?

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