Command line Argument to be parsed as integer value.

[Sika]

I have to parse the command enter in the command line argument and convert certain parameter of them into integer variable.

I can parse them but cannot convert them into integer . I have to convert the digits after '+' sign to integer variable.

The error is displayed as "Debug Assertion Error".

I am using Win32 API and code is as below:

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nShowCmd)
{

	TCHAR *cmd_line = GetCommandLine(); 
	TCHAR *token1;
	token1 = strchr(cmd_line, L'+');
	MessageBox(NULL, token1, _T("test"), NULL);
	
        int i, value=0;
	for ( i = 0; token1[ i ] != '\0'; ++i )
        {
           int digit = token1 [ i ] - '0';// get value of current digit character 
           value = 10 * value + digit;
        }

It can build sucessfully but when i run it , it shows "Debug Assertion Error"

[Little Bobby Tables]

i havent used the winapi too much before, but there might be a way to use atoi with it or the c way which is: - '0'. you could go the c++ route and use <stringstream>

[Avilius]

Did you try tracing the error with your debugger? Tell us the exact line this happens.

[Sika]

The detail in the popup error is

Debug Assertion Failed!

Program: ......WesOPC.exe
File:f:\dd\vctools\crt_bld\self_x86\crt=src\tcscpy_s.inl
line:19

Expression : (((_Src)))!=NULL

When i did debugging operation , the error is seen in token1[i] expression, in line "for ( i= 0; token1 [ i ] != '\0'; ++i)"

The error is

Unhandled exception at 0x0042847f in MinOPC.exe: 0xC0000005: Access violation reading location 0x00000000.

[Zhuge]

It looks like your token1 pointer may be null. Try using the debugger again and checking the values of your variables as you step through the program.

[modoran]

strchr returns a NULL pointer on failure, which is the case here.

[cburn11]

If you are compiling in Visual Studio, the above code is likely mixing types. TCHAR is defined as WCHAR if UNICODE or _UNICODE is defined, which are usually defined by default in visual studio projects. So your cmd_line variable is likely of type WCHAR *. You can't pass a WCHAR * to strchr which expects a CHAR *.