Is there a way to get c++ strings from the commandline like in Java?
public static void main(String[] args)
where args is an array of C++ strings?
Add a comment
|
7 Answers
Not precisely but you can come close easily.
#include <iostream>
#include <vector>
#include <string>
using namespace std;
typedef vector<string> CommandLineStringArgs;
int main(int argc, char *argv[])
{
CommandLineStringArgs cmdlineStringArgs(&argv[0], &argv[0 + argc]);
for (int i = 0; i < cmdlineStringArgs.size(); ++i)
{
cout << cmdlineStringArgs[i] << endl;
}
return 0;
}
This just uses the overloaded constructor for std::vector that takes a begining/ending iterator pair to copy the command line arguments into the vectors. It is much the same as java from there on.
You can likewise build and object around that vector with utility methods to convert arguments but there is almost no point. Also there are plenty of packages with object that deal with interpreting command line switches and such. ACE, POCO, QT, etc.. all come with such facilities.
5 Comments
sbi
What is the purpose of first copying all arguments into a
std::vector? The same loop could just as well iterate over argv directly.
Duck
@sbi - the point is that it answered OP's question. What he wants to accomplish is better directed to OP.
sbi
That's nonsense. Indexing into
argv would have answered sean's question just as well. Nowhere was he asking how to get that arguments into a vector. You've just shown him a needlessly roundabout way.Duck
He specifically wrote "where args is an array of C++ strings", not C strings.
Jasper
what's the point of that
typedef? If you ask me, it does nothing but obfuscate the code...You can use a vector to get the char array into strings.
#include <vector>
#include <string>
using namespace std;
int main (int argc, char** argv)
{
vector <string> args (argv, argv + argc);
}
5 Comments
sbi
I'd upvote this if it wouldn't be
using namespace std. (stackoverflow.com/questions/2879555/…)
xDD
@sbi That's not necessarily a bad thing to be doing inside a .cpp file. If this were a header or anything more complicated than an example 1-function file I might tend to agree with you. He is not at the same time using Boost or any other huge library, so name collisions should not be a problem.
Pepe
This really isn't the standard way to pass arguments to a C++ program.
sbi
@xDD: I disagree even in a cpp file. And I provided a link to an explanation why I think so.
sbi
@Sevis: Indeed! I overlooked that. I went in and fixed this. It's not as if there was a controversy about that as with the other issue.
Yes the main function can take 2 arguments
int main(int argc, char* argv[])
Where argc is the number of arguments and argv contains a list of the arguments.
For example if you run your program as:
MyProgram.exe hello
Then
argc = 2
argv[0] = MyProgram.exe
argv[1] = "hello"
Comments
Not built in to the language, but its very easy to implement:
#include <vector>
#include <string>
using namespace std;
int main( int argc, char *argv[] ) {
vector <string> args;
for ( int i = 0; i < argc; i++ ) {
args.push_back( argv[i] );
}
// do something with args
}
4 Comments
sbi
You don't need that loop,
std::vector has a nice ctor for that.
Sarfaraz Nawaz
You could simple use :
std::vector<string> args(argv, agrv+argc);.In C, your main function signature looks like this:
int main(int argc, char** argv).
argc contains the number of arguments passed in by the command line. The name of the executable is in position 0, and adds one to argc.
argv contains an array of strings containing the arguments. Again, position 0 is the name of the executable.
Comments
The standard C++ main() signature is
int main(int argc, char* argv[])
where argc denotes the count of commandline arguments and argv[] is an array of primitive C strings holding the commandline arguments. argv[0] is the executable, as invoked from the commandline.
Comments
If you are writing a win32 application, you can use GetCommandLineW http://msdn.microsoft.com/en-us/library/ms683156(VS.85).aspx and CommandLineToArgW http://msdn.microsoft.com/en-us/library/bb776391(VS.85).aspx
There is a comment on the CommandLineToArg page about special handling that is needed if your executable has spaces in the path and there are no arguments that you might have to handle.
