Search a particular string in a file

[Cplusplusbeginner]

I need to write a program to search a particular string in a specific file.e.g if the file is abc.dat which contains names of students in a class, I need to search for a particular name say John in that file.

One way to do that might be using the grep functionality but that will restrict the program to linux/unix only

Another way is to use the library function read() to read the entire contents into a buffer of size equal to the size of the file and then search for that particular strring. But I don't want to do that because if the file is too big unneccessary lot of memory space is required for the buffer to be allocated

So what i am looking here is any guidance which will help me to write the above program in an efficient way.

[faceboy]

Run This code and maybe it will help u

code removed per FAQ

[Coldfire]

I need to write a program to search a particular string in a specific file.e.g if the file is abc.dat which contains names of students in a class, I need to search for a particular name say John in that file.

One way to do that might be using the grep functionality but that will restrict the program to linux/unix only

Another way is to use the library function read() to read the entire contents into a buffer of size equal to the size of the file and then search for that particular strring. But I don't want to do that because if the file is too big unneccessary lot of memory space is required for the buffer to be allocated

So what i am looking here is any guidance which will help me to write the above program in an efficient way.

out of the plenty of options for file I/O in C++..........u can use this


read word by word

string sText;
ifstream in("abc.dat");
 
while( in >> sText ) //will read space-delimited one word on each iteration
{
    cout << "Read a word " << sText ;
    // Here you can do your requied string comparison
    //(sText==Name) - Bingo!
}
 

The above code will work like :
abc.dat contains e.g.
John is studying in class 10

on ist while iteration:
sText=John
on ist while iteration:
sText=is
on ist while iteration:
sText=studying
on ist while iteration:
sText=in
on ist while iteration:
sText=class
on ist while iteration:
sText=10

another way is to read file using getline func()

 
char chLine[50];//50 is line length
ifstream in("abc.dat");
 
while( in.getline(chLine,50) ) 
{
    cout << "Read line from file: " << chLine;
    // after reading one line at a time u can do whatever u want from that line
}
 

......

Good Day
Coldfire
_______________ ______
GetOneByOne CS eBooks

[Cplusplusbeginner]

out of the plenty of options for file I/O in C++..........u can use this


read word by word

string sText;
ifstream in("abc.dat");
 
while( in >> sText ) //will read space-delimited one word on each iteration
{
    cout << "Read a word " << sText ;
    // Here you can do your requied string comparison
    //(sText==Name) - Bingo!
}
 

The above code will work like :
abc.dat contains e.g.
John is studying in class 10

on ist while iteration:
sText=John
on ist while iteration:
sText=is
on ist while iteration:
sText=studying
on ist while iteration:
sText=in
on ist while iteration:
sText=class
on ist while iteration:
sText=10

another way is to read file using getline func()

 
char chLine[50];//50 is line length
ifstream in("abc.dat");
 
while( in.getline(chLine,50) ) 
{
    cout << "Read line from file: " << chLine;
    // after reading one line at a time u can do whatever u want from that line
}
 

......

Good Day
Coldfire
_______________ ______
GetOneByOne CS eBooks

Thanks! Coldfire it really helped .Thanks! once more