常用函數：

strlen 求字符串長度

strcmp 比較2個字符串是否一樣

strcat 字符串連接操作

strcpy 字符串拷貝操作

strstr 查詢子串

更具體的你可以查閱msdn

功能里面寫了阿,還要我翻譯阿
Functions
Copying:

memcpy Copy block of memory (function)
copy內存塊

memmove Move block of memory (function)
移動內存快

strcpy Copy string (function)
copy字符串

strncpy Copy characters from string (function)
從字符串里copy出字符

Concatenation:合并

strcat Concatenate strings (function)
合并字符串

strncat Append characters from string (function)
也是合并,可以指定選用前多少個字符

Comparison:比較

memcmp Compare two blocks of memory (function)
比較兩塊內存

strcmp Compare two strings (function)
比較兩個字串

strcoll Compare two strings using locale (function)

strncmp Compare characters of two strings (function)
比較兩個字符串中的字符

strxfrm Transform string using locale (function)
采用目前區域的字符排列次序來比較字符串

Searching:

memchr Locate character in block of memory (function)
在一塊內存中定位字符

strchr Locate first occurrence of character in string (function)
找第一次出現的

strcspn Get span until character in string (function)
找兩串里第一個一樣的

strpbrk Locate character in string (function)
在string里找char

strrchr Locate last occurrence of character in string (function)
最后一次出現

strspn Get span of character set in string (function)
找字符集

strstr Locate substring (function)
子串

strtok Split string into tokens (function)
分割字符串

Other:

memset Fill block of memory (function)

strerror Get pointer to error message string (function)

strlen Get string length (function)