It seems that isprint() is broken. The following program demonstrates the problem. In VS20013 it prints "test failed" in all previous versions of visual studio it prints "test passed". From this reference: http://en.cppreference.com/w/cpp/string/byte/isprint it seems that VS2013 is broken. I've opened a Microsoft Connect issue for this. #include <ctype.h> #include <iostream> int main() { int c = 9; if (isprint(c)) { std::cout << "test failed" << std::endl; } else { std::cout << "test passed" << std::endl; } return 1; }…