StringStartsWith

StringstartsWith is a string operation that determines whether a given string begins with a specified prefix. It is commonly implemented as a method or function named to resemble the startsWith behavior found in many programming languages. The operation typically takes the main string and the prefix to test, with an optional position indicating where in the main string to start the comparison. The result is a boolean: true if the substring starting at the specified position matches the prefix, and false otherwise. The default behavior is usually case-sensitive, and locale or culture handling varies by language or overload.

In practice, implementations exist under different names across languages. In JavaScript, the native method is str.startsWith(searchString [, position]). In Python, the equivalent is str.startswith(prefix [, start [, end]]). In Java, the String class provides startsWith(prefix [, offset]). In C# and other .NET languages, String.StartsWith can be used with a StringComparison parameter to control case and culture-sensitive behavior. Some environments do not provide a built-in function and rely on library helpers or custom utilities.

Usage considerations include performance and correctness for edge cases, such as empty prefixes or positions beyond the string length. Prefix checks are typically efficient, as they do not require scanning the entire string. They are commonly used for input validation, parsing, and directing control flow based on prefix matching.

See also: endsWith, includes, substring, startsWith variants in different languages.