How to replace only one character in a string in Dart?

I am trying to replace only one character in a string dart but can not find any efficient way of doing that. As string is not array in Dart I can't access the character directly by index and there is no function coming in-built which can do that. What is the efficient way of doing that?

Currently I am doing that like below:

List<String> bedStatus = currentBedStatus.split("");
bedStatus[index]='1';
String bedStatusFinal="";
for(int i=0;i<bedStatus.length;i++){
bedStatusFinal+=bedStatus[i];
}
}

index is an **int** and **currentBedStatus** is the **string** I am trying to manipulate.

**Replace at particular index:**

As `String` in dart is **immutable** [refer][1], we cannot edit something like

stringInstance.setCharAt(index, newChar)

**Efficient way** to meet the requirement would be:

String hello = "hello";
String hEllo = hello.substring(0, 1) + "E" + hello.substring(2);
print(hEllo); // prints hEllo

Moving into a **function**:

String replaceCharAt(String oldString, int index, String newChar) {
return oldString.substring(0, index) + newChar + oldString.substring(index + 1);
}
replaceCharAt("hello", 1, "E") //usage

*Note:* `index` in the above function is *zero based*.


[1]:

[To see links please register here]

You can use `replaceFirst()`.

final myString = 'hello hello';
final replaced = myString.replaceFirst(RegExp('e'), '*'); // h*llo hello

Or if you don't want to replace the first one you can use a start index:

final myString = 'hello hello';
final startIndex = 2;
final replaced = myString.replaceFirst(RegExp('e'), '*', startIndex); // hello h*llo

You can use **replaceAll().**
```
String string = 'string';
final letter='i';
final newLetter='a';
string = string.replaceAll(letter, newLetter); // strang
```

You can use this function, just modified Dinesh's answer
```
String _replaceCharAt(
{required String character,
required int index,
required String oldString}) {
if (oldString.isEmpty) {
return character;
} else if (index == oldString.length) {
return oldString.substring(0, index) + character;
} else if (index > oldString.length) {
throw RangeError('index value is out of range');
}

return oldString.substring(0, index) +
character +
oldString.substring(index + 1);
}
```

You can just use this in build function to do it.

s.replaceRange(start, end, newString)

with this line you can replace the `$` symbol with a blank space \'\'

```
'${double.parse (_priced.toString (). replaceAll (' \ $ ',' ')) ?? '\ $ 0.00'}'
```
```
String x = _with.price.toString (). ReplaceAll ('\ $', '')) ?? '\ $ 0.00',
```

Here is what you can do

```
final singleChar = 'a';
final characters = yourString.characters.toList();
characters[index] = singleChar;
yourString = characters.join('');

```

Here is how it would look like in a String extension method
```
String replaceCharAt({required String char, required int index}) {
final chars = characters.toList();
chars[index] = char;
return chars.join('');
}
```

You can also use substrings and not worry about chars.
Create substrings from string and use indices.

String ourString = "OK_AY"; // original string - length of 5
String oldChar = "_"; // the character we wanna find and replace - as type string - in this case, an underscore
String newChar = "X" // the char we wanna replace underscore with
int index = ourString.indexOf(oldChar, 0); // find the index in string where our char exists (may not exist)

//some logic here to return or skip next code if char wasn't found

//oldChar found at index 0 (beginning of string)
if (index == 0) {
ourString = newChar + ourString.substring(index+1, ourString.length);
}

//oldChar found at index 4 (end of string)
else if (index == str.length-1) {
ourString = ourString.substring(0, index) + newChar;
}

//oldChar found anywhere else between
else {
ourString = ourString.substring(0, index) + newChar + ourString.substring(index+1, ourString.length);
}

//done, ourString is now updated "OKXAY"

You can use [String.replaceRange](

[To see links please register here]

) to replace a single character of a string given a **start** and **end** index.

The method declaration looks like this:
```Dart
String replaceRange(int start, int? end, String replacement)
```

So given the string `"hello"` and you'd want to replace `"e"` with `"a"`, call:
```Dart
"hello".replaceRange(1, 2, "a")
```

So `1` is the index at `"e"` and `2` is the index after that and the result is `"hallo"`.

You could make a function to replace a single character like this:

```Dart
String replaceCharAt(String string, int index, String replacement) {
return string.replaceRange(index, index + 1, replacement);
}
```