C / C++ / MFC

An unhandled exception of type 'System.AccessViolationException' occurred in ****

Additional information: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

inline bool writeLog(nsCLog::eSeverity severity, string message)
{
	ofstream myfile;
							
		if( ((int)severity) >= mLogLevel)
		{
			myfile.open(mStrSource.c_str(), ios::in | ios::out | ios::app);

			if(!myfile.is_open())
			{
				throw "Unable to open the file: " + mStrSource;
			}
			
			myfile << "TESTE" << endl;

			myfile.close();
		}
	}

	return true;
};

virtual void __CLR_OR_THIS_CALL _Lock()
		{	// lock file instead of stream buffer
		if (_Myfile)
			_CSTD _lock_file(_Myfile);
		}

#include<stdio.h>
#include<stdlib.h>
#include<math.h>


float summation(float g);
int main(int argc,int *argv[])
{
 srand(12345);
float z;
float a=0.2,y=0.0;
int i;
for(i=0;i<5;i++)
{
float b=((float)rand()/(float)(RAND_MAX))*a;
printf("%f\n",b);

z=summation(b);
}
printf("summation:\n%f\n",z);
return 0;
} 
//=========================================================
float summation(float g)
{
		int i;
		float y[5],sum =0.0;
		float c=0.0;

			for(i=1;i<5;i++)
				{
					float z=y[i]-c;
					float t = sum+z;
					c=(t-sum)-z;
					sum=t;
					return sum;
					//printf("\n\n%f\t=",sum);
				}
}