pass argument, concatenate string

dlite922 · #1 June 18th, 2009, 11:35 PM

All i want to do in C++ is pass a few arguments, concatenate them into variable and call system()

I've gotten this far:

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#include <stdio.h>

#include <stdlib.h>

#include <string>
 
using namespace std;
 
int main(int argc,char *argv[])

{

    int i=1;

    string command;
 
//  decode arguments

    if(argc != 4) {

        printf("USAGE: %s <mount dir> <username> <password>\n\n",argv[0]);

        exit(0);

    }
 
    command = "sudo mount -t cifs //che-data.echostar.com/Shared " + argv[1] + "-ouser=" + argv[2] + ",pass=" + argv[3];

    print(command); 

    system(command); 

    return(0);

}

error: invalid operands of types "const char [51]" and "std::string*" to binary "operator+"

I know what the problem is, I don't know how to fix it. I changed argv to string, no luck.

help?

Dan

Banfa · #2 June 19th, 2009, 12:38 AM

Don't try and add everything together and then assign it to command in a single statement. Instead add everything to command using several statements.

dlite922 · #3 June 19th, 2009, 12:44 AM

Thanks I got that part working. I assigned and casted each of the argv[] to their own string var and then it worked.

But now I get an error when I try to pass the string 'command' to system() and it doesn't like it.

error: cannot convert "std::string" to "const char*" for argument "1" to "int system(const char*)"

Why can't system accept a string?
(Now I know why I love PHP)

Thanks Banfa for any help,

Dan

JosAH · #4 June 19th, 2009, 07:08 AM

Quote:

Originally Posted by dlite922

error: cannot convert "std::string" to "const char*" for argument "1" to "int system(const char*)"

Why can't system accept a string?
(Now I know why I love PHP)

Because it isn't written that way, it's a C function and strings don't exist in C; all you have to do is RTFM: here and you'll see that the c_str() function cures it all.

kind regards,

Jos

dlite922 · #5 June 19th, 2009, 05:34 PM

Thanks for your patience with a n00b. You would think the manuals would help newbies but if you think about it, it's pretty over whelming at first.

I was like that with the PHP manual, and now that's the only resource I use.

See you guys later,

Dan

weaknessforcats · #6 June 19th, 2009, 05:45 PM

Just use the combination assignment operator +=:

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 command += "sudo mount -t cifs //che-data.echostar.com/Shared ";

command += argv[1];

command += "-ouser=";

command +=  argv[2];

command += ",pass=";

command += argv[3];

pass argument, concatenate string

re: pass argument, concatenate string

re: pass argument, concatenate string

re: pass argument, concatenate string

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