c++ - 将文本文件读入 char 数组。C++ ifstream

Question

我试图将整个 file.txt 读入一个字符数组。但是有一些问题，请提出建议=]

ifstream infile;
infile.open("file.txt");

char getdata[10000]
while (!infile.eof()){
  infile.getline(getdata,sizeof(infile));
  // if i cout here it looks fine
  //cout << getdata << endl;
}

 //but this outputs the last half of the file + trash
 for (int i=0; i<10000; i++){
   cout << getdata[i]
 }

Answer 1

std::ifstream infile;
infile.open("Textfile.txt", std::ios::binary);
infile.seekg(0, std::ios::end);
size_t file_size_in_byte = infile.tellg();
std::vector<char> data; // used to store text data
data.resize(file_size_in_byte);
infile.seekg(0, std::ios::beg);
infile.read(&data[0], file_size_in_byte);

Answer 2

使用std::string：

std::string contents;

contents.assign(std::istreambuf_iterator<char>(infile),
                std::istreambuf_iterator<char>());

Answer 3

如果您打算将整个文件吸入缓冲区，则无需逐行阅读。

char getdata[10000];
infile.read(getdata, sizeof getdata);
if (infile.eof())
{
    // got the whole file...
    size_t bytes_really_read = infile.gcount();

}
else if (infile.fail())
{
    // some other error...
}
else
{
    // getdata must be full, but the file is larger...

}

Answer 4

每次阅读新行时，都会覆盖旧行。保留一个索引变量 i 并使用infile.read(getdata+i,1)然后递增 i。

Answer 5

您可以使用 Tony Delroy 的答案并结合一个小函数来确定文件的大小，然后创建该char大小的数组，如下所示：

//Code from Andro in the following question: https://stackoverflow.com/questions/5840148/how-can-i-get-a-files-size-in-c

int getFileSize(std::string filename) { // path to file
    FILE *p_file = NULL;
    p_file = fopen(filename.c_str(),"rb");
    fseek(p_file,0,SEEK_END);
    int size = ftell(p_file);
    fclose(p_file);
    return size;
}

然后你可以这样做：

//Edited Code From Tony Delroy's Answer
char getdata[getFileSize("file.txt")];
infile.read(getdata, sizeof getdata);

if (infile.eof()) {
    // got the whole file...
    size_t bytes_really_read = infile.gcount();
}
else if (infile.fail()) {
    // some other error...
}