问题描述
我想读一个系统调用的输出性病成C / C ++字符串。我可以做到这一点不使用临时文件?
Perl的
//没有文件IO
$输出=`回声hello`;
C ++
//使用文件IO
系统(回声你好> TMP);
性病:: fstream的文件(TMP);
性病::字符串s;
文件>> S;
用C的(可能是最简单的解决方案,即使不使用C ++的的iostream
)
FILE * p =的popen(回声你好,R);
性病::字符串s;
用于(为size_t计数(计数= FREAD(BUF,1,sizeof的(BUF),P));)
S + =字符串(BUF,BUF +计数);
pclose函数(对);
假设你的的iostream
有非标准的 X 的 fstream的:
X 的的fstream(INT FD)
构造器:
FILE * p =的popen(回声你好,R);
性病:: ifstream的P2(的fileno(P));
性病::字符串s;
P2>> S;
p2.close();
pclose函数(对);
使用,则不必依赖于非标准扩展到的iostream
:
的boost ::输入输出流:: file_descriptor_source P2(的fileno(P));
不幸的是,Windows是可怕的,仅适用于控制台应用程序;对于图形应用程序:
SECURITY_ATTRIBUTES秒;
sec.nLength = sizeof的(秒);
sec.bInheritHandle = TRUE;
sec.lpSecurityDescriptor = NULL;
HANDLE * H [2];
CreatePipe(安培; H [0],&放大器; H [1],&放大器;秒,0);
SetHandleInformation(H [0],HANDLE_FLAG_INHERIT,0)
STARTUPINFO SI;
memset的((无效*)及SI,0,sizeof的(SI));
si.hStdInput = INVALID_HANDLE_VALUE;
si.hStdOutput = H [1];
si.hStdError = INVALUD_HANDLE_VALUE;
si.dwFlags | = STARTF_USESTDHANDLES;
的CreateProcess(NULL,CMD / C \\回声你好\\,NULL,NULL,TRUE,0,NULL,NULL,&放大器; SI,NULL);
提高::输入输出流:: file_descriptor_source P(H [0]);
(完全未经测试)
I want to read the std output of a system call into a C/C++ string. Can I do this without using a temp file?
Perl
//without file io
$output = `echo hello`;
C++
//with file io
system ("echo hello > tmp");
std::fstream file ("tmp");
std::string s;
file >> s;
Using C's popen
(probably the simplest solution, even if it doesn't use C++'s iostream
):
FILE *p = popen("echo hello", "r");
std::string s;
for (size_t count; (count = fread(buf, 1, sizeof(buf), p));)
s += string(buf, buf + count);
pclose(p);
Assuming your iostream
has the non-standard xfstream::
xfstream(int fd)
constructor:
FILE *p = popen("echo hello", "r");
std::ifstream p2(fileno(p));
std::string s;
p2 >> s;
p2.close();
pclose(p);
Using Boost.Iostreams, you don't have to depend upon non-standard extensions to iostream
:
boost::iostreams::file_descriptor_source p2(fileno(p));
Unfortunately, Windows is horrible and _popen
only works for console applications; for a graphical app:
SECURITY_ATTRIBUTES sec;
sec.nLength = sizeof(sec);
sec.bInheritHandle = TRUE;
sec.lpSecurityDescriptor = NULL;
HANDLE *h[2];
CreatePipe(&h[0], &h[1], &sec, 0);
SetHandleInformation(h[0], HANDLE_FLAG_INHERIT, 0)
STARTUPINFO si;
memset((void *)&si, 0, sizeof(si));
si.hStdInput = INVALID_HANDLE_VALUE;
si.hStdOutput = h[1];
si.hStdError = INVALUD_HANDLE_VALUE;
si.dwFlags |= STARTF_USESTDHANDLES;
CreateProcess(NULL, "cmd /c \"echo hello\"", NULL, NULL, TRUE, 0, NULL, NULL, &si, NULL);
boost::iostreams::file_descriptor_source p(h[0]);
(completely untested)
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