Questions tagged [string]

A string is a finite sequence of symbols, commonly used for text, though sometimes for arbitrary data.

A string is a finite sequence of symbols, commonly used for text, though sometimes for arbitrary data.

Most programming languages provide a dedicated string data type or more general facilities and conventions for handling strings; as well as providing a way to denote string literals. In some programming languages everything is a string, for example in Tcl. A dedicated support library of differing sophistication is mostly provided as well.

String representations vary widely in the features they offer; the right string type can easily decrease the order of algorithms, while the wrong one might not even be able to accommodate your string data at all.

The following are some hand-picked representatives:

  • Zero-terminated Strings (aka. C-strings, ASCIZ, sz) are arrays of non-null elements, terminated by a special, null element (variants using a different terminating symbol are mostly restricted to old systems, e.g. DOS supported $).
  • Counted String (aka Pascal Strings) are arrays of arbitrary bytes, prefixed by a length indicator. Nowadays, the size for counted strings is restricted by available address space, though it was quite common to use a single byte for length (implying maximum length of 255).
  • Ropes, which are lists of segments (for example length + pointers into modifiable and non-modifiable buffers), for efficient insertion and deletion.

Many (especially functional) languages support strings as a list of base symbols.

For Unicode support, a special string of the strings type is getting common, as Unicode characters can be of arbitrary length, even in UTF-32. This enables efficient character-indexing by pushing the complexities of the character set into the string type.

In most languages, strings can be iterated over, similar to lists/arrays. In some high-level languages (in which strings are a data type unto themselves), strings are immutable, so string operations create new strings.

For text strings, many encodings are in used, though modern usage is converging on Unicode, using UTF-8 (some early adopters of Unicode instead transitioned form UCS2 to UTF-16 as a persistence format).

Windows software often adopts the WinAPI convention of using UTF-16 internally, converting for external data and persistence instead of system calls.

A String Literal is an occurrence of a string phrase in source code, generally encapsulated in dedicated delimiters (for example, in C/C++ and Java a String literal is surrounded by double quotes - "This is a String Literal").

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What is the difference between String and string in C#?

What are the differences between these two, and which one should I use? string s = "Hello world!"; String s = "Hello world!";
Lance Fisher
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How to check whether a string contains a substring in JavaScript?

Usually I would expect a String.contains() method, but there doesn't seem to be one. What is a reasonable way to check for this?
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How do I replace all occurrences of a string in JavaScript?

Given a string: s = "Test abc test test abc test test test abc test test abc"; This seems to only remove the first occurrence of abc in the string above: s = s.replace('abc', ''); How do I replace all occurrences of it?
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How do I make the first letter of a string uppercase in JavaScript?

How do I make the first character of a string uppercase if it's a letter, but not change the case of any of the other letters? For example: "this is a test" → "This is a test" "the Eiffel Tower" → "The Eiffel Tower" "/index.html" → "/index.html"
Robert Wills
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How do I read / convert an InputStream into a String in Java?

If you have a object, how should you process that object and produce a String? Suppose I have an InputStream that contains text data, and I want to convert it to a String, so for example I can write that to a log file. What is…
Johnny Maelstrom
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Why is char[] preferred over String for passwords?

In Swing, the password field has a getPassword() (returns char[]) method instead of the usual getText() (returns String) method. Similarly, I have come across a suggestion not to use String to handle passwords. Why does String pose a threat to…
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Convert bytes to a string in Python 3

I captured the standard output of an external program into a bytes object: >>> from subprocess import * >>> stdout = Popen(['ls', '-l'], stdout=PIPE).communicate()[0] >>> stdout b'total 0\n-rw-rw-r-- 1 thomas thomas 0 Mar 3 07:03 file1\n-rw-rw-r--…
Tomas Sedovic
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Does Python have a string 'contains' substring method?

I'm looking for a string.contains or string.indexof method in Python. I want to do: if not somestring.contains("blah"): continue
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How do I convert a String to an int in Java?

How can I convert a String to an int? "1234" → 1234
Unknown user
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How to check if a string contains a substring in Bash

I have a string in Bash: string="My string" How can I test if it contains another string? if [ $string ?? 'foo' ]; then echo "It's there!" fi Where ?? is my unknown operator. Do I use echo and grep? if echo "$string" | grep 'foo'; then echo…
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Creating multiline strings in JavaScript

I have the following code in Ruby. I want to convert this code into JavaScript. What is the equivalent code in JS? text = <<"HERE" This Is A Multiline String HERE
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Case insensitive 'Contains(string)'

Is there a way to make the following return true? string title = "ASTRINGTOTEST"; title.Contains("string"); There doesn't seem to be an overload that allows me to set the case sensitivity. Currently I UPPERCASE them both, but that's just silly (by…
Boris Callens
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How do I iterate over the words of a string?

How do I iterate over the words of a string composed of words separated by whitespace? Note that I'm not interested in C string functions or that kind of character manipulation/access. I prefer elegance over efficiency. My current solution: #include…
Ashwin Nanjappa
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Extract filename and extension in Bash

I want to get the filename (without extension) and the extension separately. The best solution I found so far is: NAME=`echo "$FILE" | cut -d'.' -f1` EXTENSION=`echo "$FILE" | cut -d'.' -f2` This is wrong because it doesn't work if the file name…
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Generate random string/characters in JavaScript

I want a 5 character string composed of characters picked randomly from the set [a-zA-Z0-9]. What's the best way to do this with JavaScript?
Tom Lehman
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