fstream

Why does this Stream of data end at byte 26?

由 拈花ヽ惹草 提交于 2019-12-11 02:11:51
问题 I'm still working on that bitmap I/O problem from a week ago. I got stuck again, so I decided to start with a type of I/O I was familiar with, and make it more like what I needed steadily (which is checking each byte (pixel) at a time and outputting to a file based on that byte's value). I started out with a program that read and checked each character of a text file, and output a 'Z' if it was above some threshold and output an 'A' if it was below it. That program worked great, so I decided

Is it safe to assign pos_type to uint64_t when dealing with large files (> 2GB)?

由 可紊 提交于 2019-12-11 01:18:38
问题 When trying to deal with large files (2/4GB) in cross-platform manner, is it safe to cast pos_type to uint64_t ? Platforms targeted: desktop machines running current Linux distro, Windows, Mac. Task: random binary file access ( tellp and seekp ). Sought: solution that is closest to the standards (POSIX, Win API), portable and safe. 回答1: In practice or in theory. As far as the standard is concerned, I don't think that there is a guarantee that pos_type is even convertible to an integral type;

C++ Writing to file and Console Output at the same time with simple code

由 若如初见. 提交于 2019-12-11 01:09:23
问题 I am trying to write the following entire function to a text file while still maintaining its console output functionality without having code redundancy. Is there a simple way to post an entire method's result to a file and console at the same time? #include<iostream> #include<fstream> void sports(){ cout<<"\nGame_Code\t\tGane\t\tCost\t\tStart Time\n"; cout<<"\nSP-9651\t\t Game 1 \t\t60\t\t08:00"; cout<<"\nSP-9652\t\t Game 2 \t\t60\t\t09:15"; cout<<"\nSP-9653\t\t Game 3 \t\t55\t\t09:55";

std::getline for an ifstream but using a char* instead of a string [closed]

由 北慕城南 提交于 2019-12-11 00:26:06
问题 It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center. Closed 8 years ago . I want to use the getline function with a char* . I don't want to use std::string because I have a function that takes char* as parameters and writes to them and I don't want to write a whole new one just for

Disk gets full during file write. How can I get notified about this?

由 落花浮王杯 提交于 2019-12-10 23:49:23
问题 I have a quite big object to serialize to disk, like this: if (!EngineFile.empty()) { std::ofstream OutEngineStream(EngineFile); if (!OutEngineStream) { std::cerr << "Failed to write to file \"" << EngineFile << "\"! Aborting ..." << std::endl; return -1; } engine->serialize(OutEngineStream); OutEngineStream.close(); std::cout << "\"" << EngineFile << "\" successfully wrote to disk." << std::endl; } The problem is, somtimes serialize requires larger disk space than available. e.g. there is

fstream unix problem in reading

由 ﹥＞﹥吖頭↗ 提交于 2019-12-10 21:51:47
问题 I am trying to read from binary file on UNIX. The file exists and has several data information in it. The code looks like this: fstrean fstrHandler; string strFileName; char Buf[30000]; fstrHandler.open(strFileName.c_str(), ios::in | ios::binary); fstrHandler.seekp(0, std::ios_base::beg); std::cout<< "Posi before read= "<< fstrHandler.tellg()<<endl; //*** Show after running 0 fstrHandler.read (Buf, 400); std::cout<< "Posi after read= "<< fstrHandler.tellg()<<endl; //*** Show after running 0

overwriting some text in a file using fstream and delete the rest of the file

由 人走茶凉 提交于 2019-12-10 18:14:14
问题 I am trying to write a program that read a file using fstream then, rewrite some of the text and delete the rest of the file This the code that I am trying to do #include<iostream> #include<fstream> using namespace std; int main(int argc, char **argv){ fstream *binf; fstream someFile("t.txt", ios::binary|ios::out|ios::in); int i; for(i=0;i<3;i++){ char c; someFile.seekg(i); someFile.get(c); cout<<"c:"<<c<<endl; } someFile.seekp(i++); someFile.put("Y"); someFile.seekp(i++); someFile.put("Y");

How to read and write in file with `fstream` simultaneously in c++?

由 一个人想着一个人 提交于 2019-12-10 17:52:50
问题 I have the following code #include<iostream> #include<fstream> #include<string> using namespace std; int main(void) { fstream ofile; ofile.open("test.txt", ios::in | ios::out | ios::app); for(string line; getline(ofile, line) ; ) { cout << line << endl; } ofile << "stackexchnange" << endl; ofile.close(); return 0; } test.txt contains hello world! stackoverflow Above code outputs hello world! stackoverflow And after running the code stackexchange is not appending at the end of test.txt . How

C++文件读写详解（ofstream,ifstream,fstream）

由 拈花ヽ惹草 提交于 2019-12-10 16:11:41
在看C++编程思想中，每个练习基本都是使用ofstream,ifstream,fstream，以前粗略知道其用法和含义，在看了几位大牛的博文后，进行整理和总结： 这里主要是讨论fstream的内容： [java] view plain copy print ? #include <fstream> ofstream //文件写操作 内存写入存储设备 ifstream //文件读操作，存储设备读区到内存中 fstream //读写操作，对打开的文件可进行读写操作 1.打开文件 在fstream类中，成员函数open（）实现打开文件的操作，从而将数据流和文件进行关联，通过ofstream,ifstream,fstream对象进行对文件的读写操作 函数：open（） [cpp] view plain copy print ? <span style= "font-family:Times New Roman;font-size:16px;" > public member function void open ( const char * filename, ios_base::openmode mode = ios_base::in | ios_base::out ); void open( const wchar_t *_Filename, ios_base::openmode

C++文件操作详解（ifstream、ofstream、fstream）

由 爱⌒轻易说出口 提交于 2019-12-10 15:57:20
C++ 通过以下几个类支持文件的输入输出： ofstream: 写操作（输出）的文件类 (由ostream引申而来) ifstream: 读操作（输入）的文件类(由istream引申而来) fstream: 可同时读写操作的文件类 (由iostream引申而来) 打开文件(Open a file) 对这些类的一个对象所做的第一个操作通常就是将它和一个真正的文件联系起来，也就是说打开一个文件。被打开的文件在程序中由一个流对象(stream object)来表示 (这些类的一个实例) ，而对这个流对象所做的任何输入输出操作实际就是对该文件所做的操作。 要通过一个流对象打开一个文件，我们使用它的成员函数open()： void open (const char * filename, openmode mode); 这里filename 是一个字符串，代表要打开的文件名，mode 是以下标志符的一个组合： ios::in 为输入(读)而打开文件 ios::out 为输出(写)而打开文件 ios::ate 初始位置：文件尾 ios::app 所有输出附加在文件末尾 ios::trunc 如果文件已存在则先删除该文件 ios::binary 二进制方式 这些标识符可以被组合使用，中间以”或”操作符(|)间隔。例如，如果我们想要以二进制方式打开文件"example.bin" 来写入一些数据
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