The string.h header file provides functions for comparing, copying, concatenating, and searching character arrays and arrays of larger items.

The function naming convention used in string.h determines the type of data structure(s) a function manipulates.

A function with an str prefix operates on character arrays terminated with a null character ('\0'). The str functions are

• "strcasecmp," string ignore case compare
• "strcat" concatenates strings
• "strchr" searches by character
• "strcmp" compares strings
• "strcpy" copies strings
• "strcoll" compares string lexicographically
• "strcspn" find a substring in a string
• "strerror" retrieves and error message from and errno variable
• "strlen" returns strings length
• "strpbrk" look for an occurrence of a character from one string in another
• "strrchr" searches a string for a character
• "strspn" search for a character not in one string in another
• "strstr" searches a string for a string
• "strtok" retrieves the next token or substring
• "strxfrm" transform a string to a locale

A function with a mem prefix operates on arrays of items or contiguous blocks of memory. The size of the array or block of memory is specified as a function argument. The mem functions are:

The non standard functions with a `stri' prefix operates on strings ignoring case.