char *, char, string and NSString conversion (objec-c and c++ mixing basics)

Strings are the most important elements that connect object-c and c++. Learning the processing of strings is equivalent to learning the mixing of oc and c++

char * /const char *andConversion between NSStrings

//char * /const char * changeNSString

NSString * strPath = [NSString stringWithUTF8String:filename];

//NSStringchangechar * /const char * 

const char * filePathChar = [filePath UTF8String];

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Convert char to nsstring

char myChar = 'a';
NSString * string = [NSString stringWithFormat:@"%c", myChar];

Extract a field of NSString tochar

- (unichar)characterAtIndex:(NSUInteger)index;

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C++ and oc themselves cannot be directly connected. To connect through the c API.

string to NSString

string str = [aNSString UTF8String];

NSStringTurn to string

string str("testStr");

NSString * aString = [NSString stringWithUTF8String:str.c_str()];