How to Get a Character in a String by Index

Get string character by index

The method you're looking for is charAt. Here's an example:

String text = "foo";
char charAtZero = text.charAt(0);
System.out.println(charAtZero); // Prints f

For more information, see the Java documentation on String.charAt. If you want another simple tutorial, this one or this one.

If you don't want the result as a char data type, but rather as a string, you would use the Character.toString method:

String text = "foo";
String letter = Character.toString(text.charAt(0));
System.out.println(letter); // Prints f

If you want more information on the Character class and the toString method, I pulled my info from the documentation on Character.toString.

How can I get a character in a string by index?

string s = "hello";
char c = s[1];
// now c == 'e'

See also Substring, to return more than one character.

How to get char from string by index?

First make sure the required number is a valid index for the string from beginning or end , then you can simply use array subscript notation.
use len(s) to get string length

>>> s = "python"
>>> s[3]
'h'
>>> s[6]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
IndexError: string index out of range
>>> s[0]
'p'
>>> s[-1]
'n'
>>> s[-6]
'p'
>>> s[-7]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
IndexError: string index out of range
>>> 

How to get letter from String by index? C++

std::string provides operator[] to access a character by index:

https://en.cppreference.com/w/cpp/string/basic_string/operator_at

Example:

const std::string s("hello");
const char c = s[0];
// c is set to ‘h’

How to get the index of each character of a string from the end

int i=sc.indexOf(sc.charAt(sc.length()-1));

should probably be

int i=sc.lastIndexOf(sc.charAt(sc.length()-1));

How do I access a specific index in a String in java?

You are trying to access the String's characters as if it was an array of characters. You should use the charAt method instead:

char a = inputString.charAt(2);

In order for array access to work, you should first obtain the array of characters of the given String:

char[] chars = inputString.toCharArray();
char a = chars[2];

This is useful when iterating over the characters of the String.

Getting character at a particular index in a string c#

string myString = "HelloWorld";
char myChar = myString[index];

Syntax for Returning One Character of String by Index

I think you have multiple choises.

1) Use built-in string functions instead. You can use MID function get get part of a string. So in your case something like "get one character from valPos + 1 from sReadLine.

FOR i := 0 TO 20 DO
    IF MID(sReadLine, 1, valPos + i) = '"' THEN
        EXIT;
    END_IF
    valstring := CONCAT(STR1 := valstring, STR2 := MID(sReadLine, 1, valPos + i));
END_FOR

2) Convert the ASCII byte to string. In TwinCAT systems, there is a function F_ToCHR. It takes a ASCII byte in and returns the character as string. I can't find something like that for Codesys, but i'm sure there would be a solution in some library. So please note that this won't work in Codesys without modifications:

FOR i := 0 TO 20 DO
    IF F_ToCHR(sReadLine[valPos + i]) = '"' THEN
        EXIT;
    END_IF
    valstring := CONCAT(STR1 := valstring, STR2 := F_ToCHR(sReadLine[valPos + i]));
END_FOR

3) The OSCAT library seems to have a CHR_TO_STRING function. You could use this instead of F_ToCHR in step 2.

4) You can use pointers to copy the ASCII byte to a string array (MemCpy) and add a string end character. This needs some knowledge of pointers etc. See Codesys forum for some example.

5) You can write a helper function similar to step 2 youself. Check the example from Codesys forums. That example doesn't include all characters so it needs to be updated. It's not quite elegant.

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