cmdp

Simple C++ command line arguments parser

This is a simple, header only C++ command line arguments parser library.

Options can be given as a tag value pair, in either form:

--tag value
--tag=value

A token is treated as a tag when it starts with - and is not a number, so negative values such as --offset -5 work as expected. A tag given without a value (--verbose) is recorded as a flag.

Uses

#include <cmdp/cmdp.h>

Create a cmdp::CmdParser instance.

cmdp::CmdParser parser(argc, argv);

Then read the required or optional parameters.

// read required parameters
std::string filename = parser.get<std::string>("--filename");

// read optional parameters (just pass the default values)
float expRatio = parser.get<float>("--ratio", 100.56F);

The error flag is set when a required tag is missing, or when a value cannot be converted to the requested type. A value that only partly converts, such as --count 12abc, is rejected rather than silently read as 12. Check the flag with getStatus(), or with printStatus() which also prints a summary.

API

Member	Description
get<T>(tag)	required parameter, sets the error flag if missing
get<T>(tag, def)	optional parameter, def is used if missing
has(tag)	true if the tag was given on the command line
size()	number of tags given on the command line
printStatus(os = std::cout)	print every queried parameter, returns the error state
getStatus()	returns the error state

bool values accept 1/0, true/false, yes/no and on/off, case insensitively. A valueless tag reads as true. Any other type works as long as it is default constructible and supports operator>>.

Example

cpp main file:

int main(int argc, char* argv[])
{
    // input: --filename test.jpg --ratio 15.6

    // init and parse input args
    cmdp::CmdParser parser(argc, argv);

    // read required parameters (availabe in args)
    std::string filename = parser.get<std::string>("--filename");       // test.jpg

    // read optional parameters with default values (available in args)
    float ratio = parser.get<float>("--ratio", 100.56F);                // 15.6

    // read optional parameters with default values (missing in args)
    int enable = parser.get<int>("--enable", 10);                       // 10

    // read required parameters (missing in args)
    int value = parser.get<int>("--value");                             // 0 and set error flag

    // check if any required paramters are missing.
    if (parser.printStatus()) {                                          // print all params with status
        std::cout << "Invalid Input args" << std::endl;
        return 0;
    }
    //...

    return 0;
}

Output Result parser.printStatus():

[Type  ]   Tag           Value           Status
[string] --filename      test.jpg
[float ] --ratio         15.6
[int   ] --enable        10              Default
[int   ] --value         0               Missing

Invalid Input args

Linking

This is a header only library. Add the repository root to your include path, or use CMake:

add_subdirectory(cmdp)
target_link_libraries(my_app PRIVATE cmdp::cmdp)

Building the tests

./test/build.bash          # configure, build and run the tests

or directly with CMake:

cmake -S . -B build
cmake --build build
cd build && ctest --output-on-failure

Requirements

The only build requirement is a C++ compiler that supports C++11.