在 C++ 中按完整路径打开文件
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Open file by its full path in C++
提问by
I want the user to give me the full path where the file exists and not just the file name. How do I open the file this way?
我希望用户给我文件存在的完整路径，而不仅仅是文件名。我如何以这种方式打开文件？
Is it something like this:
是不是像这样：
ifstream file;
file.open("C:/Demo.txt", ios::in);
This doesn't seem to work.
这似乎不起作用。
回答by Greg Hewgill
Normally one uses the backslash character as the path separator in Windows. So:
通常在 Windows 中使用反斜杠字符作为路径分隔符。所以：
ifstream file;
file.open("C:\Demo.txt", ios::in);
Keep in mind that when written in C++ source code, you must use the double backslash because the backslash character itself means something special inside double quoted strings. So the above refers to the file C:\Demo.txt.
请记住，当用 C++ 源代码编写时，您必须使用双反斜杠，因为反斜杠字符本身在双引号字符串中意味着一些特殊的东西。所以上面指的是文件C:\Demo.txt.
回答by Greg Hewgill
You can use a full path with the fstream classes. The folowing code attempts to open the file demo.txt in the root of the C: drive. Note that as this is an input operation, the file must already exist.
您可以对 fstream 类使用完整路径。以下代码尝试打开 C: 驱动器根目录中的文件 demo.txt。请注意，由于这是一个输入操作，因此该文件必须已经存在。
#include <fstream>
#include <iostream>
using namespace std;
int main() {
ifstream ifs( "c:/demo.txt" ); // note no mode needed
if ( ! ifs.is_open() ) {
cout <<" Failed to open" << endl;
}
else {
cout <<"Opened OK" << endl;
}
}
What does this code produce on your system?
此代码在您的系统上生成什么？
回答by phoad
The code seems working to me. I think the same with @Iothar.
代码似乎对我有用。我认为@Iohar 也是如此。
Check to see if you include the required headers, to compile. If it is compiled, check to see if there is such a file, and everything, names etc, matches, and also check to see that you have a right to read the file.
检查是否包含所需的头文件以进行编译。如果已编译，请检查是否有这样的文件，并且所有内容、名称等都匹配，并检查您是否有权读取该文件。
To make a cross check, check if you can open it with fopen..
要进行交叉检查，请检查您是否可以使用 fopen 打开它。
FILE *f = fopen("C:/Demo.txt", "r");
if (f)
printf("fopen success\n");
回答by jave.web
For those who are getting the path dynamicly... e.g. drag&drop:
对于那些动态获取路径的人......例如拖放：
Some main constructions get drag&dropped file with double quotes like:
一些主要结构使用双引号拖放文件，例如：
"C:\MyPath\MyFile.txt"
Quick and nice solution is to use this function to remove chars from string:
快速而好的解决方案是使用此函数从字符串中删除字符：
void removeCharsFromString( string &str, char* charsToRemove ) {
for ( unsigned int i = 0; i < strlen(charsToRemove); ++i ) {
str.erase( remove(str.begin(), str.end(), charsToRemove[i]), str.end() );
}
}
string myAbsolutepath; //fill with your absolute path
removeCharsFromString( myAbsolutepath, "\"" );
myAbsolutepathnow contains just C:\MyPath\MyFile.txt
myAbsolutepath现在只包含 C:\MyPath\MyFile.txt
The function needs these libraries: <iostream><algorithm><cstring>.
The function was based on this answer.
该函数需要这些库：<iostream><algorithm><cstring>.
该功能基于此答案。
Working Fiddle:http://ideone.com/XOROjq
工作小提琴：http : //ideone.com/XOROjq
