字符串相互比较和追加的问题

Problems with comparing and appending strings to each other c++

本文关键字：追加 问题 比较 字符串      更新时间：2023-10-16

我正在编写一些代码，它应该做的是返回文件的路径，而不包含文件名本身。在这里

#include <iostream>
#include <string>
#include <Windows.h>
using namespace std;
int main() {
    char binaryPath[MAX_PATH]; //I think my problems stem from the fact that 
                               //isnt truly a string
    GetModuleFileName(NULL, binaryPath, MAX_PATH); //Get filename
    string i = (string) binaryPath;
    string fileDir = "";
    int tempSlashes = 0;
    for (int x = 0; x < strlen(binaryPath); x++) {
        if (i[x] == '') { //In eclipse CDT this gives warning 1 (below)
            tempSlashes++; 
        }
    }
    for (int y = 0; y < tempSlashes; y++) {
        fileDir.append(binaryPath[y]); //Line gives warning 2
    }
    cout << fileDir;
    return 0;
}

不管怎样，小小的警告注释

Error 1:
Multiple markers at this line
- comparison with string literal results in unspecified behaviour [-
 Waddress]
- ISO C++ forbids comparison between pointer and integer [-
 fpermissive]
Error 2:
Multiple markers at this line
- Invalid arguments ' Candidates are: std::basic_string<char,std::char_traits<char>,std::allocator<char>> & append(const 
 std::basic_string<char,std::char_traits<char>,std::allocator<char>> &) std::basic_string<char,std::char_traits<char>,std::allocator<char>> & append(const 
 std::basic_string<char,std::char_traits<char>,std::allocator<char>> &, unsigned int, unsigned int) std::basic_string<char,std::char_traits<char>,std::allocator<char>> & append(const 
 char *, unsigned int) std::basic_string<char,std::char_traits<char>,std::allocator<char>> & append(const char *) std::basic_string<char,std::char_traits<char>,std::allocator<char>> & 
 append(unsigned int, char) std::basic_string<char,std::char_traits<char>,std::allocator<char>> & append(#10000, #10000) '
- invalid conversion from 'char' to 'const char*' [-fpermissive]

程序本身拒绝编译，并运行较早的。exe

我不确定我在这里做错了什么，帮助(以及解释)将是非常好的。

谢谢!

我建议向后迭代并寻找''。例如:

int len = strlen(binaryPath);
char outPath[MAX_PATH];
strcpy(outPath, binaryPath);
for (int x = len - 1; x >= 0; --x) {
    outPath[x] = 0;
    if (binaryPath[x] == '') {
        break;
    }
}

首先，在现代Win32 c++代码中，您可能希望使用Unicode代替ANSI/MBCS(因此，wchar_t代替char, std::wstring代替std::string)。

对于您的特定问题，您可能希望使用现有的Win32 API: PathRemoveFileSpec().

下面是可编译代码示例:

#define UNICODE
#define _UNICODE
#include <iostream>
#include <string>
#include <Windows.h>
#include <Shlwapi.h>
using namespace std;
#pragma comment(lib, "Shlwapi.lib")
int main()
{
    wchar_t binaryPath[MAX_PATH];
    GetModuleFileName(nullptr, binaryPath, MAX_PATH);
    PathRemoveFileSpec(binaryPath);
    // You can assign to a std::wstring as well...
    wstring fileDir = binaryPath;
    wcout << fileDir << endl;
}

下面是一个示例测试:

C:TempCppTests>cl /EHsc /W4 /nologo /MTd test.cpp
test.cpp
C:TempCppTests>test.exe
C:TempCppTests

作为一种替代方法，一旦您在原始C缓冲区中读取了带有文件名的完整路径:

wchar_t binaryPathBuffer[MAX_PATH];
GetModuleFileName(nullptr, binaryPathBuffer, MAX_PATH);

您可以将其复制到std::wstring中，然后使用其 rfind() 方法找到最后一个''的位置，然后使用std::wstring的 substr 方法提取适当的子字符串:

wstring binaryPath = binaryPathBuffer;
size_t last = binaryPath.rfind(L'');
wstring fileDir = binaryPath.substr(0, last);
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