Memo C++ Interfaces

In my development process, Although I have an impression on some C++ APIs, I can’t write them correctly and quickly. So I write this memo for my poor memory.

API-1 ShellExecute

To perform an operation on a specified file. For example:

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// open a file
ShellExecute(NULL, "open", filePath, NULL, NULL, SW_SHOW);

API-2 std::to_string and std::to_wstring

To convert a value to a string or a wide string.

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std::string s = std::to_string(2);

API-3 WritePrivateProfileString and GetPrivateProfileString

To copy a string into the specified section of an initialization file. To retrieve a string from the specified section in an initialization file. for example:

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int nValue = GetPrivateProfileInt("AppName","SectionName",nDefaultValue,filePath);

API-4 CComboBox::GetItemData/SetItemData

Sets the 32-bit value associated with the specified item in a combo box.(also in a CListCtrl, Grid…)

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int index=combobox.AddString("DisplayField");
combobox.SetItemData(index,databaseIndex);
int databaseIndex=combobox.GetItemData(index);

API-5 Shell Lightweight Utility Functions

This section describes the Windows Shell lightweight utility functions. The programming elements explained in this documentation are exported by Shlwapi.dll and defined in Shlwapi.h and Shlwapi.lib.

• String Functions
• Path Functions
• Registry Functions
• Color Palette Functions
• Miscellaneous

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wchar_t path[_MAX_PATH];
GetModuleFileNameW(NULL, path, _MAX_PATH);
PathRenameExtensionW(path, L".ini");

API-6 _variant_t

_variant_t val;
if(val.vt != VT_EMPTY){
	try{
	val.ChargeType(VT_BSTR);
	}catch(_com_error e){};
	char* cs = _com_util::ConvertBSTRToString(val.bstrVal);
	delete[] cs;
}

TRY can improve stability of the program, for example:

• double(1.23) -> string(1.23) yes
• string(1.23) -> double(1.23) yes
• string(abcd) -> double(????) error

API-7 std::unique

Removes duplicate elements that are adjacent to each other in a specified range.

std::vector v;
std::sort(v.begin(), v.end());
v.erase(std::unique(v.begin(), v.end()), v.end());

API-8 struct

Use struct only when there is data, and all others use class.

API-9 explicit constructors

use explicit for single argument constructors

class Demo{
	explicit Demo(int n);
	...
}
Demo d(1);
Demo d1 = 1;//error: Implicit conversion is not allowed

API-10 copy constructors

Use copy constructors only when you need to copy a object.

#define DISALLOW_COPY_AND_ASSIGN(TypeName)\
TypeName(const TypeName&);\
void operator = (const TypeName&)

class Demo{
	...
private:
	DISALLOW_COPY_AND_ASSIGN(Demo);//defined in private
}

API-11 TODO comments

Use TODO to comment the code that is NOT perfect, Temporary and to be done in the future.

API-12 Multiple inclusion

#define: C++ standard support #pragma once: Compiler support

#ifndef PROJECT_FILE_H_
#define PROJECT_FILE_H_
...
#endif //PROJECT_FILE_H_

API-13 UrlEscapeA

Converts characters or surrogate pairs in a URL that might be altered during transport across the Internet (“unsafe” characters) into their corresponding escape sequences.