strcasecmp

The strcasecmp function is a standard C library function used for comparing two strings in a case-insensitive manner. This means that when comparing strings, uppercase and lowercase letters are treated as equivalent. For example, "Hello" and "hello" would be considered equal by strcasecmp.

The function takes two constant character pointers, representing the strings to be compared, as arguments. It returns an integer value indicating the relationship between the two strings. A return value of zero signifies that the strings are equal. A negative return value indicates that the first string precedes the second string alphabetically, while a positive return value means the first string follows the second string alphabetically.

The strcasecmp function is typically found in the string.h header file on POSIX-compliant systems. Its primary advantage is simplifying string comparisons where case sensitivity is not a concern, such as in user input validation or searching through data where the exact casing might vary. It is a common alternative to the case-sensitive strcmp function.

While widely available on Unix-like systems, strcasecmp is not part of the standard C library as defined by ANSI C or C99. However, it is a de facto standard and is provided by many compiler implementations. For cross-platform compatibility, developers might choose to implement their own case-insensitive comparison or use platform-specific alternatives if strict adherence to standard C is required.