Something wrong in the code

[somshekhar]

void File::Write(const char* buf,const char* pErrorParameter1,const char* pErrorParameter2,const char* pErrorParameter3)

///some operation
char* pChar = (char*)(strstr(buf," '%1' "));
			if(pChar != NULL)
				strcat((char*)buf,(char*)pErrorParameter1);
			mOutputFileHandle<<buf<<"\n";

Where mOutputFileHandle is handle to a file .

When my program comes out of this function then it throws an exception.

Can anyone please help me?

[jsmith]

You are casting away constness and writing to buf anyway. That sounds dangerous, but I don't
know how you are calling Write() [ie, what is the first parameter a pointer to... writable
memory? Is the caller expecting their buffer to change, since the parameter is declared const?]

[somshekhar]

Hi Smith,
thanks for replying. can u plz refer to the following topic and can u plz help me.
http://www.cplusplus.com/forum/general/18986/

[jsmith]

The problem is as I described.

Look at all the places you call File::Write().

_tmain():26, ThrowException():13, ThrowException():16.

In all three places, you are passing a const char* to File::Write. (string::c_str() returns a const char*; you
must not change what it points to, and in _tmain(), although you've declared buf to be a char*, because it is a
string literal, it is effectively also a const char*).

const char* means don't write to the string. But your File::Write() function casts away the constness and writes
to it anyway, and this is why you are crashing.

As a general rule, a good design very rarely ever should use const_cast. A proper File::Write() implementation
would make a secondary buffer on the stack and write to it rather than to its (buf) parameter.

[somshekhar]

hi jsmith,
thanks that solves the problem.

instead of creating the buffer, i have assigned to a string object and then did the operation

void File::Write(const char* buf,const char* pErrorParameter1,const char* pErrorParameter2,const char* pErrorParameter3)
{
	if(IsFileAlreadyOpen())
	{
		
		if(!IsErrorFlagSet())
		{
			mOutputFileHandle<<buf<<"\n";
		}
		else
		{
			std::string str = buf;
			std::string str2 = "%1";
			str.replace(str.find(str2),str2.length(),pErrorParameter1);
			mOutputFileHandle<<str.c_str()<<"\n";
			
		}
		mOutputFileHandle.close();
	}
	

}