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Engineering LibreTexts

7.2: String Functions

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  • Overview

    String functions are used in computer programming languages to manipulate a string or query information about a string.[1]


    Most current programming languages include built-in or library functions to process strings. Common examples include case conversion, comparison, concatenation, find, join, length, reverse, split, substring, and trim.

    Function C++ C# Java
    case tolower(), toupper(), etc. ToLower(), ToUpper(), etc. toLowerCase(), toUpperCase(), etc.
    comparison <, >, ==, etc. <, >, ==, etc. <, >, ==, etc.
    concatenation +, += +, += +, +=
    find find() IndexOf() indexOf()
    join N/A Join() join()
    length length() Length length()
    replace replace() Replace() replace()
    reverse reverse() Reverse() N/A
    split strtok() Split() split()
    substring substr() Substring() substring()
    trim N/A Trim() trim()
    Function JavaScript Python Swift
    case toLowerCase(), toUpperCase(), etc. lower(), upper(), etc. lowercased(), uppercased()
    comparison <, >, ==, etc. <, >, ==, etc. <, >, ==, etc.
    concatenation +, += +, += +, +=
    find indexOf() find() firstIndex()
    join join() join() joined()
    length length len() count
    replace replace() replace() replacingOccurrences()
    reverse N/A string[::-1] reversed()
    split split() split() split()
    substring substring() string[start:end] string[start...end]
    trim trim() strip() trimmingCharacters()

    Key Terms

    Join character strings end-to-end.[2]
    Remove leading and trailing spaces from a string.[3]


    1. Wikipedia: Comparison of programming languages (string functions)
    2. Wikipedia: Concatenation
    3. Wikipedia: Trimming (computer programming)
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