LinuxQuestions.org - system(variable) is it possible??

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system(variable) is it possible??

i want to make a c++ program that do something like this
string str;
cin >> str;
str="cat " + str;
int rv=system(str);

is there a way to do it?

It should be fine, the only thing to watch out for is that you will probably need to convert the string to a character array check out the method c_str().

Also if the first arg in string addition is a string const you will need explicit construction:

Code:

string str;

cin >> str;

str=string("cat ") + str;

int rv=system(str.c_str());

The >> operator will only give you a section of non-whitespace, so I'd use getline instead in case someone wants to arrive at the filename with ``, or it has spaces and requires "". That involves resizing the string in advance, though:

Code:

str.resize(512);

cin.getline(&str[0], 512);

--or--

Code:

#include <iostream>

#include <string>



using namespace std;



int main()

{

  char input[512];

  cin.getline(input, 512);

  string command = string("cat ") + input;

  return system(command.c_str());

}

Save that as 'test.cpp', and after compiling run it 3 times using each of these as input:

Code:

test.cpp

`ls test.cpp`

"test.cpp"

ta0kira