What is the purpose of the strcmp function in the C language?

The strcmp function is a string comparison function in the C language, used to compare the sizes of two strings. Its function is as follows:

1. Comparing strings: The strcmp function is used to determine if two strings are equal. If the two strings are equal, the return value is 0; if the first string is less than the second string, the return value is less than 0; if the first string is greater than the second string, the return value is greater than 0.
2. String sorting: The strcmp function can be used to sort strings by comparing their sizes, thereby enabling the sorting of strings.
3. String search: the strcmp function can be used to find the position of a specified string in a string array, by comparing the strings to determine if the target string has been found.

It is important to note that the strcmp function is case-sensitive, for situations where case sensitivity matters, you can use the strcasecmp function for comparison.