...Am trying to load/capture the output of system(char* command) function to a variable, a vector. can i have any possible way to push the output to my vector? I don*t want to write the output to file and read it again.
Sample code:
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fstream>
#include <iostream>
#include <string>
#include <cstring>
#include <sstream>
#include <vector>
using namespace std;
int main()
{
vector <string> dir;
system("pwd");//here i used this to print the current directory, and i want to store this out put to my vector. something like...(below )
output=output of system("pwd");//this is not a real code,just to notice i want to put the out put to other var and push.
dir.push_back(output);
return 0;
}
Can i have any scenario to do this task, thanks.
I'd recommend doing it like this:
FILE *fp = popen("fortune","r");
char line[200];
while(!feof(fp)) {
fgets(line,200,fp);
// process here
}
pclose(fp);
If it's really performance critical it's probably better to
create a child process using fork() and pipes for stdin/stdout of that child
process to write or read from.
An example of this could be found here (http://www.microhowto.info/howto/capture_the_output_of_a_child_process_in_c.html#idp21888) if you're intested. But the popen method is probably the most simple and straightforward one in your case.
Related
I need to create a binary file with only zeroes in it. At the moment, I was able to do it for 1kb. But I need one of 2mb. Is this possible or am I missing something or using fwrite incorrectly?
#include <iostream>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
using namespace std;
int main()
{
FILE *fileAux;
fileAux = fopen("disk.dk","w+b");
fwrite("0",1024,1024*2,fileAux);
fclose(fileAux);
}
Any help is appreciated!
Buffer you are passing to it contains only 2 bytes. So you get a classical buffer overrun.
#include <iostream>
#include <time.h>
#include <string.h>
#include <stdio.h>
int main()
{
string msg;
printf("Enter the message that you wish to display as scroller: ");
getline(cin,msg);
msg=msg+". ";
int x=0;
while(1)
{
Scroll(msg);
wait(100);
system("cls");
x++;
}
cin.get();
return 0;
}
I Have this C code and all strings in the file say 'identifier "string" is undefined'. I tried including <string> instead of <string.h> but it didn't work. Why is it not working?
Add
using namespace std;
After includes (but before main). Or, better, use notion of:
std::string // instead of string
Update: I missed the point of this being C-question. I will leave this answer, but for the sake of formality, use it if you came from Google and you are working with C++.
This is C++ code, not C.
The compiler is probably getting confused because it cannot parse it, so then it finds C-like code and all identifiers do not exist.
The includes should be:
#include <iostream>
#include <ctime>
#include <string>
#include <cstdio>
You are also missing a:
using namespace std;
Plus the definitions for Scroll and wait etc.
I've started debbuging on some app, which hangs up in a loop based on readdir call.
Step by step I've cut everything but problem code, this is it:
So, in basic, it shows name of first entry and nothing more. It even does not exits, just waiting for something.
Also, I've found, that if don't lin it against libpocofoundation, it works.
But I have to do it because it used in the original app.
I'm a little bit confused, I don't use Poco in this example in any way, but it some way hangs it.
Please help me, I'm in panic :D
#include <iostream>
#include <sys/types.h>
#include <dirent.h>
#include <cstring>
#include <string>
#include <fcntl.h>
using namespace std;
int main(int argc, char *argv[])
{
const char TMP_DIR[] = "/opt";
DIR *dir = opendir(TMP_DIR);
std::cerr
<< readdir(dir)->d_name
<< readdir(dir)->d_name
<< std::endl;
return 0;
}
So... I don't know why it was happening. So I just dropped libpoco.
I'm trying to print the text "Ääkkösiä ruutuun." to console with c++. I have windows 7 and am using Code::Blocks editor. Searching on the subject I found that maybe these sort of lines would help
_setmode(_fileno(stdout), _O_U16TEXT);
wstring s{L"Ääkkösiä ruutuun."};
wcout<<s<<endl;
But when I try to compile it, I get the error: _fileno was not declared in this scope.
I have all these includes:
#include <iostream>
#include <fstream>
#include <string>
#include <vector>
#include <map>
#include <set>
#include <stdexcept>
#include <cmath>
#include <sstream>
#include <fstream>
#include <codecvt>
#include <locale>
#include <fcntl.h>
#include <io.h>
#include <stdio.h>
#include <cstdio>
#include <ostream>
what am I missing?
Also, one other thing I tried was locale, but then locale::empty wasn't found! Why doesn't my c++ have anything in it?
EDIT
Here is a picture of what my program is doing now.
It prints out just the first letter (Ä). What happens to the rest?
Ok, it seems that setmode sets it so that only one letter gets printed. (Even trying to print normal texts with multiple commands, just results in a single letter.) Without it the scandinavian letters don't print correctly, thought. They look like this:
The answer you found is for Visual Studio, not Code::Blocks.
While the C standard specifies what should in in <stdio.h>, it only specifies a minimum. Implementors may add their own functions, and should do so using an _ (underscore prefix). This is why you should NOT use that prefix. You don't know what you'll break. Microsoft clearly signaled their non-standard extensions using the correct prefix.
The answer is tagged C++, but C++ inherits the contents of <stdio.h> from C.
The line
setlocale(LC_CTYPE, ".OCP");
works!
A complete example:
#include <iostream>
#include <fstream>
#include <string>
#include <sstream>
#include <fstream>
using namespace std;
wstring readFile(const char* filename) {
wifstream wif(filename);
locale myLoc("");
//locale utf8_locale(locale(), new gel::stdx::utf8cvt<true>);
wif.imbue(myLoc);
basic_stringstream<wchar_t> wss;
wss << wif.rdbuf();
return wss.str();
}
int main() {
setlocale(LC_CTYPE, ".OCP");
wstring contents = readFile("test.txt");
wcout<<L"Does anything get printed out at all???"<<endl;
//wcout <<contents<<endl;
wstring s{L"Ääkkösiä ruutuun."};
wcout<<s<<endl;
wcout<<L"Näkyykö äkköset?"<<endl;
return 0;
}
The text read from file (utf-8) still doesn't print correctly, though.
It should be
Hei!
Täällä on kaksi riviä.
ä's go awry there.
Output:
I am experimenting with CGI in C++. I know that there are libraries which handle basic stuff, but in order to know whats going on under the hood i have been trying to parse the stdin using string datatype ---> tokenize using '= and &' then push_back into a vector. at the latter step, i am receiving segmentation fault. given below is the program where i am using cin>> to obtain user input and so on ..
#include <iostream>
#include <stdlib.h>
#include <stdio.h>
#include <vector>
#include <algorithm>
#include <string.h>
using namespace std;
int main()
{
vector <string> stuff(0);
vector<string>::iterator it;
char* bufferchar;
string buffer;
char str[size];
cout<<"Content-type: text/html\n\n"
<<"<html>"
<<"<head>"
<<"<title>CGI SCRIPT</title>"
<<"</head>"
<<"<body>"
fgets(str,20,stdin); //20 is expect size of content from html form
puts(str);
cout<<"<p>Now to break this guy apart";
int x=0;
bufferchar = strtok(str,"&=");
buffer+=bufferchar;
stuff.push_back(buffer);
while(bufferchar!=NULL){
cout<<bufferchar<<'\n'<<'\n';
bufferchar=strtok(NULL,"&=");
buffer+=bufferchar;
stuff.push_back(buffer);
}
cout<<"<br>ok does the vector iterate ?";
for (it=stuff.begin();it!=stuff.end();++it){
cout<<*it;
cout<<"<br> ok man, next <br><br>";
}
cout<<"</body>";
cout<<"</html>";
}