In lesson , we discussed how the compiler will use function templates to instantiate functions, which are then compiled. We also noted that these functions may not compile, if the code in the function template tries to perform some operation that the actual type doesn’t support (such as adding integer …
Let’s say you wanted to write a function to calculate the maximum of two numbers. You might do so like this: int max(int x, int y) { return (x < y) ? y : x; // Note: we use < instead of > because std::max uses < } While the …
The file pointer Each file stream class contains a file pointer that is used to keep track of the current read/write position within the file. When something is read from or written to a file, the reading/writing happens at the file pointer’s current location. By default, when opening a file …
File I/O in C++ works very similarly to normal I/O (with a few minor added complexities). There are 3 basic file I/O classes in C++: ifstream (derived from istream), ofstream (derived from ostream), and fstream (derived from iostream). These classes do file input, output, and input/output respectively. To use the …
The ios_base class contains several state flags that are used to signal various conditions that may occur when using streams: Although these flags live in ios_base, because ios is derived from ios_base and ios takes less typing than ios_base, they are generally accessed through ios (e.g. as std::ios::failbit). ios also …
So far, all of the I/O examples you have seen have been writing to cout or reading from cin. However, there is another set of classes called the stream classes for strings that allow you to use the familiar insertions (<<) and extraction (>>) operators to work with strings. Like …
In this section, we will look at various aspects of the iostream output class (ostream). The insertion operator The insertion operator (<<) is used to put information into an output stream. C++ has predefined insertion operations for all of the built-in data types, and you’ve already seen how you can …
The iostream library is fairly complex — so we will not be able to cover it in its entirety in these tutorials. However, we will show you the most commonly used functionality. In this section, we will look at various aspects of the input class (istream). The extraction operator As …
Input and output functionality is not defined as part of the core C++ language, but rather is provided through the C++ standard library (and thus resides in the std namespace). In previous lessons, you included the iostream library header and made use of the cin and cout objects to do …
In previous lessons, we discussed that when passing an argument by value, a copy of the argument is made into the function parameter. For fundamental types (which are cheap to copy), this is fine. But copying is typically expensive for class types (such as std::string). We can avoid making an …
