Page 292 - DCAP404 _Object Oriented Programming

Unit 13: Working with Files

getline() Notes

This function is used to read one line at a time from an input stream until some specified
criterion is met. The prototype is as follows:
getline(Array,Array_size,delimiter);

The stopping criterion can be either specified number of characters (Array_size) or the first
occurrence of a delimiter (delimiter) else the entire line (up to newline character ‘\n’) is read. If
you wish to stop reading until one of the following happens:
1. You have read 10 characters
2. You met the letter ‘m’
3. There is new line

Then the function will be called as follows:
getline(Carray,10,’m’);
The use of getline() function is demonstrated in the following example.

//Demonstration of getline() function to read a file line-wise
#include <fstream.h>
void main()
{
//Assume that the text contained in data.dat file is “Welcome to
C++”

ifstream myfile(“data.dat”);
static char Carray[10];
myfile.getline(Carray,10,’m’);
cout << Carray << endl; //the output should be “Welco”
myfile.close();
}

peek()

This function returns the ASCII code of the current character from an input file stream very much
like get() function, however, without moving the pointer to the next character. Therefore, any
number of successive call to peek() function will return the ASCII code of same character each
time. To convert the ASCII code (as returned by peek() function use char type cast) as demonstrated
in the following code program.
//Demonstration of peek() function
#include <fstream.h>
void main()

{
// Assume that the text contained in data.dat file is “Welcome to
C++”
ifstream myfile(“data.dat”);

LOVELY PROFESSIONAL UNIVERSITY 285