CODEWITHSUNDEEP
c++stringdouble-quotes
Pranav
Pranav

Reputation: 571

How to pass a string inside double quote in C++

Background:

I'm using Matlab with C++ for plotting purposes. In my present process, I need to pass a variable to matlab using matlab's function and also a string which will name the variable in matlab environment. The function I'm calling is engPutVariable(ep, "varMatlab" , varC++) where ep is the object of class (matlab)Engine, varC++ is the name of the variable inside C++ which I am passing and varMatlab will be the name of the same variable when is stored in matlab workspace. The process I use needs 4 lines of code to pass a single variable which does the same job for each variable I pass, hence I want to write a function which has the arguments of name of the variable in c++ and the name of the variable in matlab which needs to be in " " quotes.

Question:

As the function requires the name of the variable to be passed inside " " (double quotes), I want to pass a string which will take the place of varMatlab inside the quotes. I tried using inserting the " " with the string itself but it seems that is not working in this case. Any help will be really helpful.

I wrote the following function to do the same but the string name should be inside the " " which I dont know how to pass.

void putVar(double* var,int N, string name, Engine *ep){
    double row = N, col = N;
    mxArray *matlab = mxCreateDoubleMatrix(row, col, mxREAL);
    double *pa = mxGetPr(matlab);
    memcpy(pa, var, sizeof(double)*row*col);
    engPutVariable(ep, "name" , matlab);
}

Upvotes: 0

Views: 6308

Answers (3)

Tobias Langner
Tobias Langner

Reputation: 10808

Insert the " as \". As " is a special symbol for strings, it needs to be escaped. So the string "Hello World" with the quotes looks like this in C++

std::cout << "\"Hello World\"\n";

Regards Tobias

Upvotes: 2

ooga
ooga

Reputation: 15501

I believe you're confused about needing the quotes as part of the string. I think all you need is access to the c-string inside the C++ string. Get rid of the quotes and try name.c_str().

Upvotes: 1

Atmocreations
Atmocreations

Reputation: 10061

Do you mean escaping? The word "escaping" means in this context: You cannot use the character " as content of a string becauase it's part of the c++ language.

So you have to escape it in order to make the string literally contain "name". For this example, your code would look like this:

void putVar(double* var,int N, string name, Engine *ep){
    double row = N, col = N;
    mxArray *matlab = mxCreateDoubleMatrix(row, col, mxREAL);
    double *pa = mxGetPr(matlab);
    memcpy(pa, var, sizeof(double)*row*col);
    engPutVariable(ep, "\"name\"" , matlab);
}

Did I misunderstood you?

Upvotes: 1

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