you do the reading from file part, I just assigned input the variable,
#include

using namespace std;

int main()
{
char c[] = "Xlmw$mw$e$weqtpi$mrtyx$jmpi$jsv$GSWG$587:ewwmkrqirx$\'542$]syv$tvskveq$wlsyph$irgshi$xlmwjmpi$f}$ehhmrk$jsyv$xs$xli$EwGMM$zepyi$sj$iegl$glevegxiv$mr$mx2$Mr$}syv$irgshih$jmpi$xli$jmvwx$glevegxiv$wlsyph$fi$+\+2$Xli$pewx$glevegxiv$sj$xli$jmvwx$pmri$wlsyph$fi$+>+2Xli$irgshih$jmpi$wlsyph$lezi$<$pmriw$sj$xi|x$nywx$pmoi$xlmw$sri0fyx${mpp$fi$yrviehefpi2$Xli$pewx$glevegxiv$sj$xli$pewx$pmri${mpp$fi$e$+6+2";
for (int i = 0; i< sizeof c; i ++)
{
char decodedString = c[i] - 4;
cout << decodedString;
}

return 0;
}

The output was:
This is a sample input file for
#10. Your program should encode
our to the AsCII value of each c
our encoded file the first chara
he last character of the first l
e encoded file should have 8 lin