C++ 从文件中删除特定行
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原文地址: http://stackoverflow.com/questions/26576714/
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Deleting specific line from file
提问by Venraey
These are the contents of my example file:
这些是我的示例文件的内容：
abcdefg hijk lmnopqrstAB CSTAKLJSKDJD KSA FIND ME akjsdkjhwjkjhasfkajbsdh ADHKJAHSKDJH
abcdefg hijk lmnopqrstAB CSTAKLJSKDJD KSA FIND ME akjsdkjhwjkjhasfkajbsdh ADHKJAHSKDJH
I need to find and delete the 'FIND ME' inside of the file so the output would look like this:
我需要找到并删除文件中的“FIND ME”，这样输出将如下所示：
abcdefg hijk lmnopqrstAB CSTAKLJSKDJD KSA akjsdkjhwjkjhasfkajbsdh ADHKJAHSKDJH
abcdefg hijk lmnopqrstAB CSTAKLJSKDJD KSA akjsdkjhwjkjhasfkajbsdh ADHKJAHSKDJH
I have tried the following method of doing getline and then writing all of the contents except the FIND ME into a temporary file and then rename the temporary file back.
我尝试了以下方法来执行 getline，然后将除 FIND ME 之外的所有内容写入临时文件，然后将临时文件重命名回。
string deleteline;
string line;
ifstream fin;
fin.open("example.txt");
ofstream temp;
temp.open("temp.txt");
cout << "Which line do you want to remove? ";
cin >> deleteline;
while (getline(fin,line))
{
if (line != deleteline)
{
temp << line << endl;
}
}
temp.close();
fin.close();
remove("example.txt");
rename("temp.txt","example.txt");
but it doesn't work. Just as a side note: the file has NO newline/linefeeds. So the file contents are all written in 1 line.
但它不起作用。正如旁注：该文件没有换行符/换行符。所以文件内容都写在1行。
EDIT:
编辑：
FIXED CODE:
固定代码：
while (getline(fin,line))
{
line.replace(line.find(deleteline),deleteline.length(),"");
temp << line << endl;
}
This gets me the results I expected. Thank you everyone for helping!
这让我得到了我预期的结果。谢谢大家的帮助！
采纳答案by gmas80
Try this:
尝试这个：
line.replace(line.find(deleteline),deleteline.length(),"");
回答by Cuinn Herrick
In case anyone would like it I have converted Venraey's useful code to a function:
如果有人愿意，我已将 Venraey 的有用代码转换为函数：
#include <iostream>
#include <fstream>
void eraseFileLine(std::string path, std::string eraseLine) {
std::string line;
std::ifstream fin;
fin.open(path);
std::ofstream temp; // contents of path must be copied to a temp file then renamed back to the path file
temp.open("temp.txt");
while (getline(fin, line)) {
if (line != eraseLine) // write all lines to temp other than the line marked fro erasing
temp << line << std::endl;
}
temp.close();
fin.close();
const char * p = path.c_str(); // required conversion for remove and rename functions
remove(p);
rename("temp.txt", p);}
回答by X1NK3R
I'd like to clarify something. Although the answer provided by gmas80 could work, for me, it didn't. I had to modify it somewhat, and here's what I ended up with:
我想澄清一些事情。尽管 gmas80 提供的答案可以工作，但对我来说却没有。我不得不稍微修改一下，这就是我最终得到的结果：
position = line.find(deleteLine);
if (position != string::npos) {
line.replace(line.find(deleteLine), deleteLine.length(), "");
}
Another thing that didn't satisfy me was that it left blank lines in the code. So I wrote another thing to delete the blank lines:
另一件让我不满意的事情是它在代码中留下了空行。所以我写了另一件事来删除空行：
if (!line.empty()) {
temp << line << endl;
}
