UNIX for Advanced & Expert Users

int main(void)
{
        int columns=6;
        float *f=malloc(sizeof(float)*columns);
        float comp=0.0f;

        // Read binary data piped into stdin
        while(fread(f, sizeof(float), columns, stdin) == columns)
        {
                // Never compare floating point with == unless you know
                // you're really going to get the exact value right
                // down to the last bit.  Choose a value sufficiently close
                // to equal instead.
                if(abs(f[0]-comp) < 0.000001)
                        // If the row matches, write it back to standard out.
                        fwrite(f, sizeof(float), columns, stdout);
        }
}

double buffer[]={x, y, Z(i,j)}; 
fwrite(buffer, sizeof(double), sizeof(buffer), Mesh);

fwrite(buffer, sizeof(double), sizeof(buffer)/sizeof(double), Mesh);