OC与c++混编数据类型转换

1.NSString转化为UNICODE String：(NSString*)fname ＝ @“Test”;char fnameStr[10];memcpy(fnameStr, [fname cStringUsingEncoding:NSUnicodeStringEncoding], 2*([fname length]));

与strcpy相比，memcpy并不是遇到'\0'就结束，而是一定会拷贝完n个字节

2.NSString 转化为 char *NSString * str＝ @“Test”;const char * a =[str UTF8String];

3.char * 转化为 NSString

NSString *str=[NSString stringWithCStringencoding:NSUTF8StringEncoding];

4.char * 转化 NSData方法一： 

 char * a = (char*)malloc(sizeof(byte)*16); 

 NSData *data = [NSData dataWithBytes: a length:strlen(a)]; 

方法二：    

转换为NSString： - (id)initWithUTF8String:(const char *)bytes   

 然后用NSString的 - (NSData *)dataUsingEncoding:(NSStringEncoding)encoding

5.NSData 转化 char *NSData data ；  char* a=[data bytes];

6.NSData 转化 NSString;

NSData* data;

NSString* aStr= ［NSString alloc] initWithData:dataencoding:NSASCIIStringEncoding];

7.NSString 转化 NSData对象NSData* xmlData = [@"testdata" dataUsingEncoding:NSUTF8StringEncoding];

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std::string->char

char szDst[256];

std::string strSrc = "hoge";

//const char* pszDst = strSrc.c_str();

sprintf(szDst, "%s", strSrc.c_str());

char->std::string

char szSrc[]="hoge";

std::string strDst = std::string(szSrc);

char->NSString

char szSrc[]="hoge";

NSString *nsstrDst = [NSString stringWithUTF8String: szSrc];

NSString->char

char szDst[256];

NSString *nsstrSrc = @"hgoe";

//const char* pszDst = [nsstrSrc UTF8String];

sprintf(szDst, "%s", [nsstrSrc UTF8String]);

std::string转NSString

std::string_string("hello");

NSString*str=[NSStringstringWithCString:_string.c_str()encoding:[NSStringdefaultCStringEncoding]];

NSString转std::string

NSString*nsfaceName=@"HELLO";

constchar*lpfaceName=[nsfaceName UTF8String];

std::stringstrFaceName=[nsfaceName UTF8String];