IO operations help

Hello,

Today i am playing with IO's, and here is the example that i want to work out:

Code:

#include <iostream>
#include <fstream>
#include <cstdlib>
#include <cstring>

void openFile(std::fstream &out, std::string fileName, int x){


    switch (x){
		case 'rt':
		out.open (fileName.c_str(),std::ios::in);
		break;
		case 'wt':
		out.open (fileName.c_str(),std::ios::out);
		break;
		case 'at':
		out.open (fileName.c_str(),std::ios::app);
		break;
		case 'rb':
		out.open (fileName.c_str(),std::ios::in | std::ios::binary);
		break;
		case 'wb':
		out.open (fileName.c_str(),std::ios::out | std::ios::binary);
		break;
	}

	if ( !out.is_open()){
		std::cout << "Cannot open file: in_file! Line:" << __LINE__<< std::endl;
		exit(EXIT_FAILURE);
	}
}

int main(int argc, char **argv){

char buffer[100]; 
std::fstream out_file;
std::fstream in_file;


openFile(out_file,"example.txt",'wt');  // WORKS
out_file << "Radi-";
out_file.close();
out_file.clear();

openFile(in_file,"example.txt",'rt');  // WORKS
in_file.read(buffer, 5); 
std::cout << buffer; 
in_file.close();
in_file.clear();

openFile(out_file,"example.txt",'at');  // DOES NOT APPEND
out_file << "Radio";
out_file.close();
out_file.clear();
	
openFile(in_file,"example.txt",'rt'); //  WORKS but prints out this strange character
in_file.read(buffer, 10); 
std::cout << buffer; 
in_file.close();
in_file.clear();

openFile(out_file,"example.bin",'wb'); // not binary - correction
out_file << "Radik\n";
out_file.close();
out_file.clear();

openFile(out_file,"example.bin",'rb'); // not binary - correction
out_file.read(buffer, 5); 
std::cout << buffer; 
out_file.close();
out_file.clear();

return 0;

}

so i am opening and closing the files and reading and writing to them. the problems are stated in the code. Can someone explainwhat is going on..

output: Radi-Radi-Radik

ok i learned how to use read and write

Code:

int main(int argc, char **argv){

char buffer[100]; 
std::fstream out_file;
std::fstream in_file;
int a[10];

for (int i = 0 ; i<10 ;i++)
  a[i] = i;

openFile(out_file,"example.txt",'wt');
out_file.write("RADI",4);
out_file.close();
out_file.clear();

openFile(in_file,"example.txt",'rt');
in_file.read(buffer, 4); 
std::cout << buffer; 
in_file.close();
in_file.clear();

openFile(out_file,"example.txt",'at');
out_file.write("RADI-------",10);
out_file.close();
out_file.clear();
	
openFile(in_file,"example.txt",'rt');
in_file.read(buffer, 10); 
std::cout << buffer; 
in_file.close();
in_file.clear();

openFile(out_file,"example.bin",'wb');
out_file.write((char *)&a , (sizeof(int)*10));
out_file.close();
out_file.clear();
int v[10];
openFile(out_file,"example.bin",'rb');
out_file.read((char *)&v, (sizeof(int)*10)); 
for(int i =0; i<10;i++)
std::cout <<v[i] <<"\n"; 
out_file.close();
out_file.clear();

return 0;

}

but still i get some strange characters when i print out my strings...

RADI�RADI�0