Mega Code Archive
Reverses the first N characters within a file
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#include <iostream>
#include <fstream>
#include <cstdlib>
using namespace std;
int main(int argc, char *argv[])
{
long n, i, j;
char ch1, ch2;
if(argc!=3) {
cout << "Usage: Reverse <filename> <num>\n";
return 1;
}
fstream finout(argv[1], ios::in | ios::out | ios::binary);
if(!finout) {
cout << "Cannot open input file.\n";
return 1;
}
n = atol(argv[2]) - 1;
for(i=0, j=n; i < j; ++i, --j) {
finout.seekg(i, ios::beg);
finout.get(ch1);
finout.seekp(j, ios::beg);
finout.put(ch1);
if(!finout.good()) {
cout << "Error reading or writing characters.";
finout.clear();
break;
}
}
finout.close();
if(!finout.good()) {
cout << "A file error occurred.";
return 1;
}
return 0;
}
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