尝试将文本字段值写入 c++ 中的文件
我对这个错误感到抓狂。
------ Build started: Project: shotfactorybatchgen, Configuration: Debug Win32 ------
shotfactorybatchgen.cpp
c:\documents and settings\administrator\my documents\visual studio 2010\projects\shotfactorybatchgen\shotfactorybatchgen\Form1.h(307): error C2664: 'fprintf' : cannot convert parameter 2 from 'System::String ^' to 'const char *'
No user-defined-conversion operator available, or
Cannot convert a managed type to an unmanaged type
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========
我浏览了整个互联网，但找不到答案。这是发生错误的代码。
private: System::Void button1_Click(System::Object^ sender, System::EventArgs^ e) {
Decimal value;
if(!Decimal::TryParse(textBox4->Text, value)) {
MessageBox::Show("Non-numeric characters detected in 'Wait Time' filed", "Oops", MessageBoxButtons::OK, MessageBoxIcon::Warning);
} else {
if(!Decimal::TryParse(textBox3->Text, value)) {
MessageBox::Show("Non-numeric characters detected in 'Max Upload' filed", "Oops", MessageBoxButtons::OK, MessageBoxIcon::Warning);
} else {
FILE *OutFile = fopen("run.bat","w");
fprintf(OutFile,"@ECHO OFF\r\nC:\\Python26\\python.exe factory.py");
if(factoryname->Text != ""){
fprintf(OutFile," -f ");
fprintf(OutFile,factoryname->Text);
}
fclose(OutFile);
}
}
}
有什么想法吗？这是一个简单的 Windows 窗体应用程序。我正在使用 Visual Studio C++ 2010
谢谢
专栏
I am tearing my hair out over this error.
------ Build started: Project: shotfactorybatchgen, Configuration: Debug Win32 ------
shotfactorybatchgen.cpp
c:\documents and settings\administrator\my documents\visual studio 2010\projects\shotfactorybatchgen\shotfactorybatchgen\Form1.h(307): error C2664: 'fprintf' : cannot convert parameter 2 from 'System::String ^' to 'const char *'
No user-defined-conversion operator available, or
Cannot convert a managed type to an unmanaged type
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========
I have looked all around the interwebs but I can not find an answer. Here is the code that the error is happening in.
private: System::Void button1_Click(System::Object^ sender, System::EventArgs^ e) {
Decimal value;
if(!Decimal::TryParse(textBox4->Text, value)) {
MessageBox::Show("Non-numeric characters detected in 'Wait Time' filed", "Oops", MessageBoxButtons::OK, MessageBoxIcon::Warning);
} else {
if(!Decimal::TryParse(textBox3->Text, value)) {
MessageBox::Show("Non-numeric characters detected in 'Max Upload' filed", "Oops", MessageBoxButtons::OK, MessageBoxIcon::Warning);
} else {
FILE *OutFile = fopen("run.bat","w");
fprintf(OutFile,"@ECHO OFF\r\nC:\\Python26\\python.exe factory.py");
if(factoryname->Text != ""){
fprintf(OutFile," -f ");
fprintf(OutFile,factoryname->Text);
}
fclose(OutFile);
}
}
}
Any ideas? It is a simple windows form application. I am using Visual Studio C++ 2010
Thanks
Colum
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如果
factoryname->Text标识了一个属性，那么它的 getter 可能会抛出 CLR 异常，在这种情况下，您将泄漏文件句柄OutFile。考虑不使用fopen等。它是一个C库函数，并且有更好的替代品，例如std::ofstream。或者，由于您有 .NET 可用，您可以使用
StreamWriter，它可以让您传递System::String，从而也避免您的转换问题：C++/CLI 将采用当范围退出时，请注意关闭
writer。If
factoryname->Textidentifies a property, then its getter may throw a CLR exception, in which case you will leak the file handleOutFile. Consider not usingfopen, etc. It's a C library function and there are better alternatives such asstd::ofstream.Alternatively, as you have .NET available, you could use
StreamWriterwhich will let you passSystem::Stringand thus avoid your conversion problem as well:C++/CLI will take care of closing the
writerwhen the scope is exited.这只是一个转换错误：
此处发布了可能的解决方案：
在 C++/CLI 中 char* 和 System::String 之间转换的最佳方式是什么
打开文件
将 System::String 转换为 const char*
It's simply a conversion error:
Possible solution is posted here:
What is the best way to convert between char* and System::String in C++/CLI
Opening Files
Convert System::String to const char*