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in Technique[技术] by (71.8m points)

write and read string to binary file C++

Im having problems writing string into a binary file. This is my code:

ofstream outfile("myfile.txt", ofstream::binary);
std::string text = "Text";
outfile.write((char*) &text, sizeof (string));
outfile.close();

Then, I try to read it,

char* buffer = (char*) malloc(sizeof(string));
ifstream infile("myfile.txt", ifstream::binary);    
infile.read(buffer, sizeof (prueba));
std::string* elem = (string*) buffer;
cout << *elem;
infile.close();

I just cant get it to work. I am sorry, I am just desperate. Thank you!

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by (71.8m points)

the line

outfile.write((char*) &text, sizeof (string));

is not correct

sizeof(string) doesn't return the length of the string, it returns the sizeof the string type in bytes.

also do not cast text to char* using a C cast, you can get hold of the char* by using the appropriate member function text.c_str()

you can simply write

outfile << text;

instead.


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