Initilizing a vector of strings where I already know all the values to populate it with C++

Question

I have spent well over an hour researching this before I came to you guys for help. I am using visual studio 2012 and I just installed the update 2.

I have this constructor

Lexer::Lexer(istream &source1, ostream& listing1)
:source(source1), listing(listing1)
{
vector<string> tempVec = { 
    "and", "begin", "boolean", "break", "call", "end", "else", "false", "halt",
        "if", "input", "integer", "is", "loop", "not", "null", "newline", "or", "output", "procedure"
        "return", "then", "true", "var"
};




tokenToStringVector = tempVec;

for (int k= 0; k < tokenToStringVector.size(); k++)
{
    string key = tokenToStringVector[k];
    lexemeToTokenMap[key] = Token(k); // Function-style type cast
}
}

My professor wrote the header, and I wrote the code. I am getting this error which I cannot figure out:

1>c:\users\sam\dropbox\compiler project\lexical analyzer\lexer.cpp(8): error C2552: 'tempVec' : non-aggregates cannot be initialized with initializer list
1>          'std::vector<_Ty>' : Types with a base are not aggregate
1>          with
1>          [
1>              _Ty=std::string
1>          ]

I don't understand why it will not let me initialize it like this. I could make an array, and then a loop to add to the vector, but I am already just using the vector to populate a map, so there must be a more logical way to do this.

Thanks SO! You guys are always so helpful!

PLEASE NOTE: If the answer is not a simple formatting error, please don't correct the code, just point me in the right direction. This is a graded assignment and I am an honest student and I want to learn this myself.

Ok, from the replies and re-reading the SO post someone posted.

Visual Studio does not support this, even though it is valid in C++ 2011

Thanks guys, I guess I do just need to make an array.

My Professor told me to do it similar to this and he uses some Linux gcc compiler that does support this.

EDIT: Ok, so Microsoft has an alpha version that supports this. I guess i'll just make an array and transfer it.

THANKS FOR THE HELP!!!!

It should work. Are you sure you have C++11 support switched on? — juanchopanza, Apr 18 '13 at 16:07
http://stackoverflow.com/questions/12654394/initializer-list-not-working-with-vector-in-visual-studio-2012 — stardust, Apr 18 '13 at 16:08
By the way, your "procedure" and "return" tokens are being merged into a single const string in the declaration. They are not separated by a **`,`** in the source code. You're gonna need to fix that. — WhozCraig, Apr 18 '13 at 16:09

yngccc · Accepted Answer · 2013-04-18T16:21:40.263

4

vc++ does not support initializer list.
I do not know whether is is supported in update 2, but the standard library will certainly not support it even if the feature is in.

Edit: update 2 does not support initializer list either.

edited Apr 18 '13 at 16:21

answered Apr 18 '13 at 16:09

yngccc

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It does as of the Visual C++ Compiler November 2012 CTP. – zennehoy Apr 18 '13 at 16:11
1

@zennehoy ya, and it is full of bugs... – yngccc Apr 18 '13 at 16:12

score 1 · Answer 2 · answered Apr 18 '13 at 16:14

For old C++, the only option is:

const char *constants[] = { "and", "begin", "boolean", "break", "call", "end", "else", "false", "halt",
    "if", "input", "integer", "is", "loop", "not", "null", "newline", "or", "output", "procedure"
    "return", "then", "true", "var" };

vector<string> values(constants,&constants[sizeof(constants)/sizeof(constants[0])]);

score 1 · Answer 3 · edited May 23 '17 at 12:28

1

Your code is valid C++11, but apparently your toolchain is not happy with this (mine is, by the way, Apple LLVM 4.2 Clang). Consider this as an alternative:

Lexer::Lexer(istream &source1, ostream& listing1)
    :source(source1), listing(listing1)
{
    static const char *reserved[] =
    {
        "and", "begin", "boolean", "break", "call",
        "end", "else", "false", "halt", "if", "input",
        "integer", "is", "loop", "not", "null", "newline",
        "or", "output", "procedure", "return", "then",
        "true", "var"
    };

    std::copy(std::begin(reserved), std::end(reserved),
              back_inserter(tokenToStringVector));

    // rest of your code.
}

Note: I took the liberty of fixing the merged "procedure" and "return" strings, which I'm fairly sure you neglected to separate with a , by accident.

edited May 23 '17 at 12:28

Community

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answered Apr 18 '13 at 16:17

WhozCraig

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No need to copy, you can use a static member and initialise the array directly in the initialiser list from that array. – Konrad Rudolph Apr 18 '13 at 17:22
@KonradRudolph completely true if the static reserved[] array is class-static and not static to the constructor body (and, in fact, very good advice to do so). I know if `reserved[]` is a class static (or general static) declared outside of the constructor body-scope then assuredly you can use the vector constructor that accepts begin+end iterators for automatic construction. As written, `reserved[]` isn't available for initializer-list construction. – WhozCraig Apr 18 '13 at 18:42
Yes, I was implying that in my comment (“static *member* ”). I should have elaborated. – Konrad Rudolph Apr 18 '13 at 18:43
@KonradRudolph As should have I when responding while answering the question, not accounting for the fact that is totally a valid (and IMHO correct) alternative. Even if not used by the OP, I shall update the answer at some point to include this better (and correct) construct. Thanks for the input and advice, sir. – WhozCraig Apr 18 '13 at 18:47

score 0 · Answer 4 · answered Apr 18 '13 at 16:08

0

The error message says the problem. You are trying to initialize a vector of strings with an initializer list, as if it were an array. You can initialize an array with an initializer list, but not a vector. Probably what you want is to create an array from your initializer list, and then initialize the vector from your array.

answered Apr 18 '13 at 16:08

antlersoft

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It is valid C++11 though. – juanchopanza Apr 18 '13 at 16:09
Yes, I have been reading online that it is valid in the new version, that is why I mentioned that I had the latest update. – Samuel French Apr 18 '13 at 16:10

score 0 · Answer 5 · edited May 23 '17 at 12:04

0

Syntax var = { x, y, z } can only be used on aggregates and your compiler protest that (for him) vector<string> is not an aggregate.

edited May 23 '17 at 12:04

Community

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answered Apr 18 '13 at 16:09

Offirmo

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And for anybody else `vector` is not an aggregate. That's not the problem. The problem is support for uniform initialization syntax, which was added to the language by C++11. – Pete Becker Apr 18 '13 at 16:15

Initilizing a vector of strings where I already know all the values to populate it with C++

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