Solved

Question about BOOST_FOREACH

Posted on 2014-01-25
1
172 Views
Last Modified: 2014-09-30
Suppose I have a std::vector of double called myVec, and a std::map of type <int, double> called myMap. Why is it that the following works

BOOST_FOREACH(double x, myVec) x = 10.0;

Open in new window

and the following gives an error
BOOST_FOREACH(pair<int,double> y, myMap) 
cout << y.first << "\t" << y.second << endl;

Open in new window

so that I need to use

pair<int,double> y;
BOOST_FOREACH(y, myMap) cout << y.first << "\t" << y.second << endl;

Open in new window

instead?
0
Comment
Question by:Rothbard
1 Comment
 
LVL 3

Accepted Solution

by:
kuroji earned 200 total points
ID: 40088317
It's the comma in the expression
pair<int, double>
The C Preprocessor is not type aware.

Write it like this and you're good to go
typedef std::map<int, double>::value_type map_value_type;

BOOST_FOREACH(map_value_type y, myMap) 
    std::cout << y.first << "\t" << y.second << std::endl;

Open in new window

0

Featured Post

Free Tool: Port Scanner

Check which ports are open to the outside world. Helps make sure that your firewall rules are working as intended.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Introduction This article is the first in a series of articles about the C/C++ Visual Studio Express debugger.  It provides a quick start guide in using the debugger. Part 2 focuses on additional topics in breakpoints.  Lastly, Part 3 focuses on th…
What is C++ STL?: STL stands for Standard Template Library and is a part of standard C++ libraries. It contains many useful data structures (containers) and algorithms, which can spare you a lot of the time. Today we will look at the STL Vector. …
The viewer will learn how to use the return statement in functions in C++. The video will also teach the user how to pass data to a function and have the function return data back for further processing.
The viewer will learn how to clear a vector as well as how to detect empty vectors in C++.

749 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question