iostream

I want to write a print function for a class AutoData that has information about cars in it. With this print function, I would ideally like to print out a vector that contains many different class objects. I have already written get functions for each element of the objects, but I am still a bit unsure of how to go about using those to write a function to print out the data in the following format: mpg:cylinders:displacement:horsepower:weight:acceleration:modelYear:origin:carName For example: 10.0:8:360.0:215.0:4615.:14.0:70:1:ford f250 10.0:8:307.0:200.0:4376.:15.0:70:1:chevy c20 11.0:8:318.0

I found this question already asked, but the answer everybody gives is std::cout << std::setw(5) << std::setfill('0') << value << std::endl; which is fine for positive numbers, but with -5, it prints: 000-5 Is there a way to make it print -0005 or to force cout to always print at least 5 digits (which would result in -00005) as we can do with printf? std::cout << std::setw(5) << std::setfill('0') << std::internal << -5 << '\n'; // ^^^^^^^^ Output: -0005 std::internal Edit: For those those that care about such things, N3337 ( ~c++11 ), 22.4.2.2.2 : The location of any padding is determined

This question already has answers here : Closed 5 years ago . Why does std::cout convert volatile pointers to bool? (4 answers) Consider this (artificial) example: #include <cstdio> #include <iostream> int main() { volatile char test[] = "abc"; std::printf("%s\n", test); std::cout << test << "\n"; } Compiling it with GCC and running gives the following output: $ g++ test.cc $ ./a.out abc 1 As you can see printf prints the string correctly while cout prints 1 . Why does writing to cout produces 1 in this case? The only suitable overload of operator<< is that for bool , so the array is converted

my problem is that I create a folder(name is IconResources) under src , in IconResources there are many pictures. Directory is like this: ProjectName src package 1 package 2 IconResources(this is the target folder) I want to list all picture files name and do something with those pictures. And I found that File.list() only works in IDE, if I export project to a jar to make a standalone, it cannot work. So I searched and found that I should use inputstream and outputstream. Now I find i/o stream can works well for single file. But I want to use inputstream and outputstream to read folder

I'm reading data from a stream into a char array of a given length, and I'd like to make the maximum width of read to be large enough to fit in that char array. The reason I use a char array is that part of my specification is that the length of any individual token cannot exceed a certain value, so I'm saving myself some constructor calls. I thought width() did what I wanted, but I was apparently wrong... EDIT: I'm using the stream extraction operators to perform the extraction, since these are flat text files with values separated by whitespace. char x[4]; cin.width(4); cin >> x; cout << x;

Create a flat text file in c++ around 50 - 100 MB with the content 'Added first line' should be inserted in to the file for 4 million times using old style file io fopen the file for write. fseek to the desired file size - 1. fwrite a single byte fclose the file The fastest way to create a file of a certain size is to simply create a zero-length file using creat() or open() and then change the size using chsize() . This will simply allocate blocks on the disk for the file, the contents will be whatever happened to be in those blocks. It's very fast since no buffer writing needs to take place.

How can I override a C++ standard-library class function? In my application, I use ofstream objects in many different places of code. And now I want to open files in a different permission mode in Linux, Ubuntu. But open function of ofstream has no parameter to specify the permission mode of the file it creats. Now I want to override open() function of ofstream class so it will get a parameter to specify the permissions for user access. For starters, to clarify your terminology, the STL usually refers to the subset of the C++ standard library containing the containers, iterators, and