将文件内容字符对读入数组

发布于 2024-12-07 18:21:37 字数 561 浏览 1 评论 0原文

在C++中，如何将文件的内容读入字符串数组？我需要一个由空格分隔的字符对组成的文件，如下所示：

cc cc cc cc cc cc
cc cc cc cc cc cc
cc cc cc cc cc cc
cc cc cc cc cc cc

c 可以是任何字符，包括空格！尝试：

ifstream myfile("myfile.txt");
int numPairs = 24;
string myarray[numPairs];

for( int i = 0; i < numPairs; i++) {
    char read;
    string store = "";

    myfile >> read;
    store += read;

    myfile >> read;
    store += read;

    myfile >> read;

    myarray[i] = store;
}

问题是这只是跳过空格，因此导致错误的值。我需要改变什么才能让它识别空格？

原文

In C++, how can I read the contents of a file into an array of strings? I need this for a file that consists of pairs of chars separated by spaces as follows:

cc cc cc cc cc cc
cc cc cc cc cc cc
cc cc cc cc cc cc
cc cc cc cc cc cc

c can be any char, including space! Attempt:

ifstream myfile("myfile.txt");
int numPairs = 24;
string myarray[numPairs];

for( int i = 0; i < numPairs; i++) {
    char read;
    string store = "";

    myfile >> read;
    store += read;

    myfile >> read;
    store += read;

    myfile >> read;

    myarray[i] = store;
}

The problem is that this just skips spaces alltogether, hence leading to wrong values. What do I need to change to make it recognize spaces?

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背叛残局 2024-12-14 18:21:37

这是预期的行为，因为默认情况下 operator>> 会跳过空格。

解决方案是使用 get 方法，这是一种低级操作，从流中读取原始字节而不进行任何格式化。

char read;
if(myfile.get(read)) // add some safety while we're at it
    store += read;

顺便说一句，VLA（大小不固定的数组）在 C++ 中不是标准的。您应该指定一个常量大小，或者使用诸如vector之类的容器。

That's expected behavior, since operator>>, by defaults, skips whitespace.

The solution is to use the get method, which is a low level operation that reads raw bytes from the stream without any formatting.

char read;
if(myfile.get(read)) // add some safety while we're at it
    store += read;

By the way, VLAs (arrays with a non constant size) are non standard in C++. You should either specify a constant size, or use a container such as vector.

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z祗昰~ 2024-12-14 18:21:37

如果输入与您所说的完全相同，则以下代码将起作用：

ifstream myfile("myfile.txt");
int numPairs = 24;
string myarray[numPairs];

EDIT: if the input is from STDIN
for( int i = 0; i < numPairs; i++) {
    myarray[i] = "";
    myarray[i] += getchar();
    myarray[i]+= getchar();
    getchar(); // the space or end of line

}

EDIT: If we don't now the number of pairs beforehand
      we shoud use a resizable data structure, e.g. vector<string>
vector<string> list;
// read from file stream
while (!myfile.eof()) {
    string temp = "";
    temp += myfile.get();
    temp += myfile.get();
    list.push_back(temp);
    myfile.get();
}

If the input is exact like you say the following code will work:

ifstream myfile("myfile.txt");
int numPairs = 24;
string myarray[numPairs];

EDIT: if the input is from STDIN
for( int i = 0; i < numPairs; i++) {
    myarray[i] = "";
    myarray[i] += getchar();
    myarray[i]+= getchar();
    getchar(); // the space or end of line

}

EDIT: If we don't now the number of pairs beforehand
      we shoud use a resizable data structure, e.g. vector<string>
vector<string> list;
// read from file stream
while (!myfile.eof()) {
    string temp = "";
    temp += myfile.get();
    temp += myfile.get();
    list.push_back(temp);
    myfile.get();
}

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