stdstring

问题 I'm pretty familiar with most of C++ but one area I've avoided has been IO streams, mainly because I've been using it on embedded systems where they're not appropriate. Recently I've had to become familiar with them, however, and I'm struggling to figure out something that I feel should be simple. What I'm looking for a relatively efficient way to read a fixed number of characters from a C++ stream into a std::string . I could easily read into a temporary char array with the read() method and

问题 I've seen several other posts about converting QString to std::string, and it should be simple. But somehow I'm getting an error. My code is compiled into a VS project using cmake (I'm using VS express), so there's no issue with the QT libraries, and the GUI that I wrote works besides this part. I have a QComboBox cb that holds the names to some objects, and a QLineEdit lineEdit that allows me to specify the name of the object that I am looking for. It should run a function that is tested and

来源： https://stackoverflow.com/questions/62912056/assigning-const-stdstring-to-stdstring-in-c

来源： https://stackoverflow.com/questions/62912056/assigning-const-stdstring-to-stdstring-in-c

来源： https://stackoverflow.com/questions/61141894/why-is-stdstrings-member-operator-not-lvalue-ref-qualified

问题 Here I have a 2d vector of char - std::vector<std::vector<char>> solution = { {"O","1"}, {"T","0"}, {"W","9"}, {"E","5"}, {"N","4"} }; Printing anything from first column - prints fine. cout << "In main - " << solution [ 1 ] [ 0 ]; // Prints T But when I try to access element of second column. cout << "In main - " << solution [ 1 ] [ 1 ]; // Prints blank space - I can't seem to understand why's the case. After quiet amount of searching I tried by putting single quotes around every element.

问题 I'm having some trouble figuring out the exact semantics of std::string.length() . The documentation explicitly points out that length() returns the number of characters in the string and not the number of bytes. I was wondering in which cases this actually makes a difference. In particular, is this only relevant to non-char instantiations of std::basic_string<> or can I also get into trouble when storing UTF-8 strings with multi-byte characters? Does the standard allow for length() to be

问题 Many developers and library authors have been struggling with compile-time strings for quite a few years now - as the standard (library) string, std::string , requires dynamic memory allocation, and isn't constexpr. So we have a bunch of questions and blog posts about how to get compile-time strings right: Conveniently Declaring Compile-Time Strings in C++ Concatenate compile-time strings in a template at compile time? C++ Compile-Time string manipulation (off-site) Compile-time strings with

问题 Many developers and library authors have been struggling with compile-time strings for quite a few years now - as the standard (library) string, std::string , requires dynamic memory allocation, and isn't constexpr. So we have a bunch of questions and blog posts about how to get compile-time strings right: Conveniently Declaring Compile-Time Strings in C++ Concatenate compile-time strings in a template at compile time? C++ Compile-Time string manipulation (off-site) Compile-time strings with

问题 Many developers and library authors have been struggling with compile-time strings for quite a few years now - as the standard (library) string, std::string , requires dynamic memory allocation, and isn't constexpr. So we have a bunch of questions and blog posts about how to get compile-time strings right: Conveniently Declaring Compile-Time Strings in C++ Concatenate compile-time strings in a template at compile time? C++ Compile-Time string manipulation (off-site) Compile-time strings with