Question

我正在使用boost::format（而不是std::因为我正在使用c ++ 98）来格式化我传递给system()调用的字符串。

获取c_str()创建的字符串的format时，它似乎在字符串的中途终止。使用文字值创建的相同sting没有相同的问题。这是怎么回事？

根据BOOST_VERSION使用Boost 1.46.1 。

#include <boost/format.hpp>
#include <iostream>
#include <string>

int main(int argc, char** argv)
{
    const std::string my_str = "echo '/%1%/ some other stuff'";
    boost::format fmtr(my_str);
    fmtr % "sleep 3";   // should read: echo '/sleep 3/ some other stuff'

    std::cout << "1: " << fmtr.str() << "\n";          // 1. echo '/sleep 3/ some other stuff'  (OK)
    std::cout << "2: " << fmtr.str().c_str() << "\n";  // 2. echo '/sleep 3                     (BAD)

    // Try the c_str of a string not created through boost::format
    const std::string finished = "echo '/sleep 3/ some other stuff'";
    std::cout << "3: " << finished.c_str() << "\n";    // 3. echo '/sleep 3/ some other stuff'  (OK)

    // Try copying the string from format to see if that makes any difference (it doesn't)
    std::string copy = fmtr.str();
    std::cout << "4: " << copy.c_str() << "\n";        // 4. echo '/sleep 3                     (BAD)
    return 0;
}

将c_str()传递给我的system()电话会导致错误：

sh -c: line 0: unexpected EOF while looking for matching `''

大概是因为它也沿着琴弦中途完成了。

Answer 1

正确包含您的程序正常工作：ideone

#include <boost/format.hpp>
#include <iostream>
#include <string>

int main()
{
    const std::string my_str = "echo '/%1%/ some other stuff'";
    boost::format fmtr(my_str);
    fmtr % "sleep 3";   // should read: echo '/sleep 3/ some other stuff'

    std::cout << "1: " << fmtr.str() << "\n";          // 1. echo '/sleep 3/ some other stuff'  (OK)
    std::cout << "2: " << fmtr.str().c_str() << "\n";  // 2. echo '/sleep 3                     (BAD)

    // Try the c_str of a string not created through boost::format
    const std::string finished = "echo '/sleep 3/ some other stuff'";
    std::cout << "3: " << finished.c_str() << "\n";    // 3. echo '/sleep 3/ some other stuff'  (OK)

    // Try copying the string from format to see if that makes any difference (it doesn't)
    std::string copy = fmtr.str();
    std::cout << "4: " << copy.c_str() << "\n";        // 4. echo '/sleep 3                     (BAD)
}

您应修复包含并返回主要类型，然后重试。如果错误的行为持续存在，则可能是您破坏了c ++和/或boost库的版本。

为什么std / boost :: format导致这个c_str（）行为？

1 个答案: