c语言中何时引用#include <string.h>

c语言中何时引用#include <string.h>

当使用到string.h中的函数时，需要引用头文件string.h
string.h为C语言库函数头文件之一，包含了内存处理及字符串处理函数。
1 内存处理相关函数，包括memcmp, memcpy, memset等。
2 字符串处理函数，包括strcpy, strcmp, strlen,strstr等。
当用到相关函数时，推荐引用string.h。

gets,puts是 stdio.h里面的
string.h里面有这些,MSDN上的
String-Manipulation Routines
Routine Use
_mbscoll, _mbsicoll, _mbsncoll, _mbsnicoll Compare two multibyte-character strings using multibyte code page information (_mbsicoll and _mbsnicoll are case-insensitive)
_mbsdec, _strdec, _wcsdec Move string pointer back one character
_mbsinc, _strinc, _wcsinc Advance string pointer by one character
_mbslen Get number of multibyte characters in multibyte-character string; dependent upon OEM code page
_mbsnbcat Append, at most, first n bytes of one multibyte-character string to another
_mbsnbcmp Compare first n bytes of two multibyte-character strings
_mbsnbcnt Return number of multibyte-character bytes within supplied character count
_mbsnbcpy Copy n bytes of string
_mbsnbicmp Compare n bytes of two multibyte-character strings, ignoring case
_mbsnbset Set first n bytes of multibyte-character string to specified character
_mbsnccnt Return number of multibyte characters within supplied byte count
_mbsnextc, _strnextc, _wcsnextc Find next character in string
_mbsninc. _strninc, _wcsninc Advance string pointer by n characters
_mbsspnp, _strspnp, _wcsspnp Return pointer to first character in given string that is not in another given string
_mbstrlen Get number of multibyte characters in multibyte-character string; locale-dependent
sprintf, _stprintf Write formatted data to a string
strcat, wcscat, _mbscat Append one string to another
strchr, wcschr, _mbschr Find first occurrence of specified character in string
strcmp, wcscmp, _mbscmp Compare two strings
strcoll, wcscoll, _stricoll, _wcsicoll, _strncoll, _wcsncoll, _strnicoll, _wcsnicoll Compare two strings using current locale code page information (_stricoll, _wcsicoll, _strnicoll, and _wcsnicoll are case-insensitive)
strcpy, wcscpy, _mbscpy Copy one string to another
strcspn, wcscspn, _mbscspn, Find first occurrence of character from specified character set in string
_strdup, _wcsdup, _mbsdup Duplicate string
strerror Map error number to message string
_strerror Map user-defined error message to string
strftime, wcsftime Format date-and-time string
_stricmp, _wcsicmp, _mbsicmp Compare two strings without regard to case
strlen, wcslen, _mbslen, _mbstrlen Find length of string
_strlwr, _wcslwr, _mbslwr Convert string to lowercase
strncat, wcsncat, _mbsncat Append characters of string
strncmp, wcsncmp, _mbsncmp Compare characters of two strings
strncpy, wcsncpy, _mbsncpy Copy characters of one string to another
_strnicmp, _wcsnicmp, _mbsnicmp Compare characters of two strings without regard to case
_strnset, _wcsnset, _mbsnset Set first n characters of string to specified character
strpbrk, wcspbrk, _mbspbrk Find first occurrence of character from one string in another string
strrchr, wcsrchr,_mbsrchr Find last occurrence of given character in string
_strrev, _wcsrev,_mbsrev Reverse string
_strset, _wcsset, _mbsset Set all characters of string to specified character
strspn, wcsspn, _mbsspn Find first substring from one string in another string
strstr, wcsstr, _mbsstr Find first occurrence of specified string in another string
strtok, wcstok, _mbstok Find next token in string
_strupr, _wcsupr, _mbsupr Convert string to uppercase
strxfrm, wcsxfrm Transform string into collated form based on locale-specific information
vsprintf, _vstprint Write formatted output using a pointer to a list of arguments

引用字符处理函数

需要用字符串函数时，做预编译声明，strXXX()这类函数……

这些不用
一般用到str开通的函数要#include
比如 strlen strcmp strcat等等

gets/puts都是基本输入输出函数
在头文件"stdio.h"中
"string.h"中是字符串操作函数
比如strcpy/strcat等
一般C语言教材附录都会有基本操作函数及其头文件位置
你可以自己看一下

当你用到如strlen（），strcpy（），strcmp（）这样的函数时要用到string。h头函数