CODEWITHSUNDEEP
c++swiftobjective-cnsstringobjective-c++
Can Yoldas
Can Yoldas

Reputation: 212

Converting string from C++ to Swift

I am trying to use C++ functions in Swift. To do that, I use an Objective-C wrapper. I am not familiar with Objective-C and C++ so much.

My wrapper function takes Swift String as a parameter from textField. And inside of C++ I encrypt the passed string and return it.

Here is my C++ function:

string StringModifier::encryptString(string str) {
    int i;
    for(i=0; (i<100 && str[i] != '\n'); i++) {
        str[i] = str[i] + 2;
    }
    return str;
}

And inside of the wrapper:

StringModifier stringModifier;

-(NSString*)encryptString:(NSString*)str; {
    string strng = [str UTF8String];
    string finalString = stringModifier.encryptString(strng);
    NSString *result = [NSString stringWithCString: finalString.c_str() encoding:[NSString defaultCStringEncoding]];
    return result;
}

The output of encryptString("Helloworld") is "Jgnnqyqtnf¬√√0*?" and after a couple of times calling this method, it throws an EXC_BAD_ACCESS error.

How can I solve this problem?

Upvotes: 0

Views: 339

Answers (1)

George
George

Reputation: 30341

You need to check for the null character (\0) in C++.

Change your for-loop to this:

for(i=0; (i<100 && str[i] != '\n' && str[i] != '\0'); i++) {
    str[i] = str[i] + 2;
}

Even better, loop depending on how big the string is:

string StringModifier::encryptString(string str) {
    for (int i = 0; i < str.size() && str[i] != '\n'; i++) {
        str[i] = str[i] + 2;
    }
    return str;
}

Upvotes: 1

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