Reading INI file using Boost Property Tree when value section does not exist

Question

I'm using Boost.PropertyTree to read INI file:

read_ini( "myIni.ini", pt );
string s=pt.get<std::string>("Section1.value1");

If section doesn't contain value1 record then Boost raises exception.

How to read INI file in an elegant way and give a default value to s in case Section1.value1 does not exist?

I guess you mean that you use the [Boost Property tree library](http://www.boost.org/doc/libs/1_56_0/doc/html/property_tree.html)? — Some programmer dude, Sep 10 '14 at 08:10

score 3 · Accepted Answer · answered Sep 10 '14 at 08:10

3

Using Boost.Optional:

s = pt.get_optional<std::string>("Section1.value1").get_value_or("default");
//     ^^^^^^^^^^^^                                     ^^^^^^^^  ^^^^^^^

answered Sep 10 '14 at 08:10

Piotr Skotnicki

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score 1 · Answer 2 · answered Sep 10 '14 at 08:11

1

You should state which boost library you are referring to in your question. The answer is found in the documentation.

You can use get_optional.

answered Sep 10 '14 at 08:11

Peter

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score 1 · Answer 3 · answered Jun 07 '16 at 20:44

You are using what the documentation calls the "throwing version" of get(). However, there is also a "default value" version which takes an extra argument -- the default value. As a bonus, the type specification is usually not needed since the type is deduced from the default value.

If the default value is "default" then you simply use

string s=pt.get("Section1.value1", "default");

The other answers mention the use of get_optional(), but this isn't exactly what you want since the value of string s is not optional (even though Section.value1 in the INI file is optional).

Reading INI file using Boost Property Tree when value section does not exist

3 Answers3