To link C++ code, you need to use the g++ command, not the gcc command. When compiling, the gcc command knows that it’s compiling C++ code because of the .cpp suffix (but it’s a good idea to use the g++ command anyway). When linking, the gcc command just sees a bunch of .o files. The … Read more
getchar() is a standard function that gets a character from the stdin. getch() is non-standard. It gets a character from the keyboard (which may be different from stdin) and does not echo it.
Interesting little question. According to the C++11 standard, sect. 21.4.2.9, basic_string(const charT* s, const Allocator& a = Allocator()); Requires: s shall not be a null pointer. Since the standard does not ask the library to throw an exception when this particular requirement is not met, it would appear that passing a null pointer provoked undefined … Read more
It’s the other way around. When ios::ate is set, the initial position will be the end of the file, but you are free to seek thereafter. When ios::app is set, all output operations are performed at the end of the file. Since all writes are implicitly preceded by seeks, there is no way to write … Read more
The standard library favours elementary algorithms. Containers and algorithms should be independent of each other if possible. Likewise, algorithms that can be composed of existing algorithms are only rarely included, as shorthand. If you require a transform if, you can trivially write it. If you want it /today/, composing of ready-mades and not incur overhead, … Read more
It means not found. It is usually defined like so: static const size_t npos = -1; It is better to compare to npos instead of -1 because the code is more legible.
A: Almost always [use a vector instead of an array]. Vectors are efficient and flexible. They do require a little more memory than arrays, but this tradeoff is almost always worth the benefits. That’s an over-simplification. It’s fairly common to use arrays, and can be attractive when: the elements are specified at compile time, e.g. … Read more
Declaring vector in the std namespace is undefined behavior. So, your code might work, but it also might not, and the compiler is under no obligation to tell you when your attempt won’t work. That’s a gamble, and I don’t know that avoiding the inclusion of a standard C++ header is worth that. See the … Read more
valarray is kind of an orphan that was born in the wrong place at the wrong time. It’s an attempt at optimization, fairly specifically for the machines that were used for heavy-duty math when it was written — specifically, vector processors like the Crays. For a vector processor, what you generally wanted to do was … Read more
If you need to iterate over a queue then you need something more than a queue. The point of the standard container adapters is to provide a minimal interface. If you need to do iteration as well, why not just use a deque (or list) instead?