有时候可能用到某个库的某些函数接口，但是这个库有可能在某个平台上被裁减过了，接口支持不全，如果你想跨平台使用，就会出问题

因此在使用之前进行检测是否存在这个函数，还是很有必要的，xmake提供了方便的api，可以批量检测某个库的一些函数：

例如：

add_target("test")        -- 检测libc库中，对宽字符操作的接口是否存在，检测条件：检查wchar.h、stdlib.h中是否有函数声明      add_cfuncs("libc", nil,         {"wchar.h", "stdlib.h"},            "wcscat",                                                                          "wcsncat",                                                                          "wcscpy",                                                                          "wcsncpy",                                                                          "wcslcpy",                                                                          "wcslen",                                                                          "wcsnlen",                                                                          "wcsstr",                                                                          "wcscasestr",                                                                          "wcscmp",                                                                          "wcscasecmp",                                                                          "wcsncmp",                                                                          "wcsncasecmp",                                                                          "wcstombs",                                                                          "mbstowcs")        -- 检测pthread库中，是否存在pthread_mutex_init, pthread_create接口，相当于检测了pthread是否存在      -- 第一个参数是库类型、别名，可以随便写      add_cfuncs("posix", nil,        "pthread.h",                        "pthread_mutex_init", "pthread_create")        -- 检测pthread库中，是否存在pthread_mutex_init, pthread_create接口，相当于检测了pthread是否存在      -- 这个检测更加严格，同时检测了libpthread.a静态库是否存在这个接口的定义，如果链接不通过，就检测失败      -- xmake会在检测时，尝试链接-lpthread      add_cfuncs("posix", "pthread",  "pthread.h",                        "pthread_mutex_init", "pthread_create")

可以执行： xmake f -v 看到实际的检测信息，这里随便摘取了一段tbox中检测信息：

checking for the c include string.h ... ok  checking for the c include stdlib.h ... ok  checking for the c function strlen ... ok  checking for the c function sincosf ... no  checking for the c include wchar.h ... ok  checking for the c function wcscmp ... ok  checking for the c function wcsncat ... ok  checking for the c include dlfcn.h ... ok  checking for the c function dlopen ... ok  checking for the links polarssl ... ok  checking for the c include polarssl/polarssl.h ... ok  checking for the c function strcat ... ok  checking for the c function wcsstr ... ok  checking for the c function wcscat ... ok  checking for the c function sincos ... no  checking for the c function memcpy ... ok  checking for the c function sqrtf ... ok  checking for the c function wcsnlen ... ok  checking for the c function acosf ... ok  checking for the links pthread, dl, m, c ... ok  checking for the c include sys/stat.h ... ok  checking for the c function open ... ok  checking for the c function strnlen ... ok  checking for the c function system ... ok  checking for the links z ... ok  checking for the c include zlib/zlib.h ... ok  checking for the c function strncat ... ok  checking for the c function wcsncpy ... ok  checking for the c function gmtime ... ok  checking for the c include signal.h ... ok  checking for the c include setjmp.h ... ok  checking for the c function sigsetjmp ... ok  checking for the c function sinf ... ok  checking for the c function strncmp ... ok  checking for the c function memmove ... ok  checking for the c function strncasecmp ... ok  checking for the c function strlcpy ... ok  checking for the links sqlite3 ... ok  checking for the c include sqlite3/sqlite3.h ... ok  checking for the c include sys/sem.h ... ok  checking for the c include sys/ipc.h ... ok  checking for the c function semtimedop ... no  checking for the c function wcscpy ... ok  checking for the c function sqrt ... ok  checking for the c function strcmp ... ok  checking for the c function strcasecmp ... ok  checking for the c function semget ... ok  checking for the c include unistd.h ... ok  checking for the c function sysconf ... ok  checking for the c function memset ... ok  checking for the c function getpagesize ... ok  checking for the c include semaphore.h ... ok  checking for the c function sem_init ... ok  checking for the c function strncpy ... ok  checking for the c function localtime ... ok  checking for the c include ifaddrs.h ... ok  checking for the c function getifaddrs ... ok  checking for the c function strcpy ... ok  checking for the c function gethostname ... ok  checking for the c function wcslcpy ... ok  checking for the c include dirent.h ... ok  checking for the c function opendir ... ok  checking for the c function wcslen ... ok  checking for the c function cos ... ok  checking for the c include sys/time.h ... ok  checking for the c function gettimeofday ... ok  checking for the c function signal ... ok  checking for the c function strstr ... ok  checking for the c function exp ... ok  checking for the c function log2f ... ok  checking for the c function sin ... ok  checking for the c function log2 ... ok  checking for the c function cosf ... ok  checking for the c include pthread.h ... ok  checking for the c function pthread_mutex_init ... ok  checking for the c function fmodf ... ok  checking for the c function wcstombs ... ok  checking for the c function fmod ... ok  checking for the c function memcmp ... ok  checking for the c function atan2f ... ok  checking for the c function atan2 ... ok  checking for the c function atanf ... ok  checking for the c function atan ... ok  checking for the c function powf ... ok  checking for the c function pow ... ok  checking for the c function asinf ... ok  checking for the c function asin ... ok  checking for the c function pthread_create ... ok

最后的检测结果会自动输出到config.h中（如果有启用的话）：

#define TB_CONFIG_LIBC_HAVE_MEMCPY  #define TB_CONFIG_LIBC_HAVE_MEMSET  #define TB_CONFIG_LIBC_HAVE_MEMMOVE  #define TB_CONFIG_LIBC_HAVE_MEMCMP  #define TB_CONFIG_LIBC_HAVE_MEMMEM  #define TB_CONFIG_LIBC_HAVE_STRCAT  #define TB_CONFIG_LIBC_HAVE_STRNCAT  #define TB_CONFIG_LIBC_HAVE_STRCPY  #define TB_CONFIG_LIBC_HAVE_STRNCPY  #define TB_CONFIG_LIBC_HAVE_STRLCPY  #define TB_CONFIG_LIBC_HAVE_STRLEN  #define TB_CONFIG_LIBC_HAVE_STRNLEN  #define TB_CONFIG_LIBC_HAVE_STRSTR  #define TB_CONFIG_LIBC_HAVE_STRCASESTR  #define TB_CONFIG_LIBC_HAVE_STRCMP  #define TB_CONFIG_LIBC_HAVE_STRCASECMP  #define TB_CONFIG_LIBC_HAVE_STRNCMP  #define TB_CONFIG_LIBC_HAVE_STRNCASECMP  #define TB_CONFIG_LIBC_HAVE_WCSCAT  #define TB_CONFIG_LIBC_HAVE_WCSNCAT  #define TB_CONFIG_LIBC_HAVE_WCSCPY  #define TB_CONFIG_LIBC_HAVE_WCSNCPY  #define TB_CONFIG_LIBC_HAVE_WCSLCPY  #define TB_CONFIG_LIBC_HAVE_WCSLEN  #define TB_CONFIG_LIBC_HAVE_WCSNLEN  #define TB_CONFIG_LIBC_HAVE_WCSSTR  #define TB_CONFIG_LIBC_HAVE_WCSCMP  #define TB_CONFIG_LIBC_HAVE_WCSCASECMP  #define TB_CONFIG_LIBC_HAVE_WCSNCMP  #define TB_CONFIG_LIBC_HAVE_WCSNCASECMP  #define TB_CONFIG_LIBC_HAVE_WCSTOMBS  #define TB_CONFIG_LIBC_HAVE_MBSTOWCS  #define TB_CONFIG_LIBC_HAVE_GMTIME  #define TB_CONFIG_LIBC_HAVE_MKTIME  #define TB_CONFIG_LIBC_HAVE_LOCALTIME  #define TB_CONFIG_LIBC_HAVE_GETTIMEOFDAY  #define TB_CONFIG_LIBC_HAVE_SIGNAL  #define TB_CONFIG_LIBC_HAVE_SETJMP  #define TB_CONFIG_LIBC_HAVE_SIGSETJMP  #define TB_CONFIG_LIBC_HAVE_BACKTRACE  #define TB_CONFIG_LIBC_HAVE_SYSTEM  #define TB_CONFIG_LIBM_HAVE_LOG2  #define TB_CONFIG_LIBM_HAVE_LOG2F  #define TB_CONFIG_LIBM_HAVE_SQRT  #define TB_CONFIG_LIBM_HAVE_SQRTF  #define TB_CONFIG_LIBM_HAVE_ACOS  #define TB_CONFIG_LIBM_HAVE_ACOSF  #define TB_CONFIG_LIBM_HAVE_ASIN  #define TB_CONFIG_LIBM_HAVE_ASINF  #define TB_CONFIG_LIBM_HAVE_POW  #define TB_CONFIG_LIBM_HAVE_POWF  #define TB_CONFIG_LIBM_HAVE_FMOD  #define TB_CONFIG_LIBM_HAVE_FMODF  #define TB_CONFIG_LIBM_HAVE_ATAN  #define TB_CONFIG_LIBM_HAVE_ATANF  #define TB_CONFIG_LIBM_HAVE_ATAN2  #define TB_CONFIG_LIBM_HAVE_ATAN2F  #define TB_CONFIG_LIBM_HAVE_COS  #define TB_CONFIG_LIBM_HAVE_COSF  #define TB_CONFIG_LIBM_HAVE_SIN  #define TB_CONFIG_LIBM_HAVE_SINF  #define TB_CONFIG_LIBM_HAVE_EXP  #define TB_CONFIG_LIBM_HAVE_EXPF  #define TB_CONFIG_POSIX_HAVE_POLL  #define TB_CONFIG_POSIX_HAVE_PTHREAD_MUTEX_INIT  #define TB_CONFIG_POSIX_HAVE_PTHREAD_CREATE  #define TB_CONFIG_POSIX_HAVE_SOCKET  #define TB_CONFIG_POSIX_HAVE_OPENDIR  #define TB_CONFIG_POSIX_HAVE_DLOPEN  #define TB_CONFIG_POSIX_HAVE_OPEN  #define TB_CONFIG_POSIX_HAVE_GETHOSTNAME  #define TB_CONFIG_POSIX_HAVE_GETIFADDRS  #define TB_CONFIG_POSIX_HAVE_SEM_INIT  #define TB_CONFIG_POSIX_HAVE_GETPAGESIZE  #define TB_CONFIG_POSIX_HAVE_SYSCONF  #define TB_CONFIG_POSIX_HAVE_SCHED_YIELD  #define TB_CONFIG_SYSTEMV_HAVE_SEMGET

之后就可以在代码中，包含这个config.h来判断是否需要实际调用这个接口了，如果要多c++代码的接口进行检测，只需把名字改成：

add_cxxfuncs(...)

就行了，更加详细的检测设置，可以参考 依赖包的添加和自动检测机制