Stream from a String Instead of CIN in C++
TL;DR: You can stream from a string instead of STDIN. Code is simple and is listed below. A project I did recently had a requirement to overload the >> operator use and STDIN to load data. The problem was not the overload itself, but the fact that testing would introduce a manual side. To get around that, I needed a way to stream data from a string instead of STDIN. The solution is presented below:
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#ifndef POLYMORPH_MEMSTREAM_H #define POLYMORPH_MEMSTREAM_H #include <streambuf> #include <istream> struct membuf : std::streambuf { membuf(char const *base, size_t size) { char *p(const_cast<char *>(base)); this->setg(p, p, p + size); } }; /** * Usage: * imemstream in(data, size); * in >> value; */ struct imemstream : virtual membuf, std::istream { imemstream(char const *base, size_t size) : membuf(base, size), std::istream(static_cast<std::streambuf *>(this)) { } }; |
To use it, all you need to do is: Create a string:
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const char * str = "1.0\n2.0\n3.0\n4.0\n5.0\n6.0\n7.0\n8.0\n9.0\n10.0" |
It…read more
