1. Review of Strings
which include file needs to be used for string manipulation?
what using statement needs to be included fro string manipulation?
how is a string assigned a value? Can a string be initialized at declaration?
how is getline() different from extraction operator?
what does this line do? string s1=”hi” + ’ ’ + ”there”;
how are strings compared? Which one is greater? hell bell hello
how can the size of a string be determined? Can string size be changed? What is the size of this string? string s2=”hello”; is there a problem with this statement? cout << s2[4];
assuming string s3=”C++ is fun”; what do the following functions do?
s3.substr(4,2);
s3.find(’+’);
s3.rfind(’+’);
s3.find_first_of(”is”);
s3.find_last_of(”is”);
s3.insert(3,2,’ ’);
s3.replace(1,3,”--”);
s3.append(”!!”);
s3.erase(0,3);

2. Input/Output

3. Streams C++ uses streams for input and output
stream - is a sequence of data to be read (input stream) or a sequence of data generated by the program to be output (output stream)
by default only standard streams are declared: cin (console input) cout (console output)
files are used to store information on permanent basis
to do file input/output <fstream> needs to be included
as well as using std::ifstream; and using std::ofstream;
an input or output stream needs to be declared:
ifstream fin; // input stream
ofstream fout; // output stream
before C++ program can read from or write to a file stream, the stream needs to be connected to a file. This is referred to as opening the file:
fin.open(”myfile.dat”); // opening file

4. Streams (Cont.) a string variable can be used as file name
c_str() function has to be applied to the string:
string filename=”myfile.dat”;
fin.open(filename.c_str());
after stream variable has been connected to a file, extraction and insertion operators can be used with a stream:
fin >> var1 >> var2 >> var3;
after the file is opened all the operations on the file is done through associated stream
before program finishes every stream needs to closed:
fin.close(); // closing file
function eof() returns true if end of input file has been reached:
while(!fin.eof()){ … }

5. I/O Error Checking
function fail() returns true if previous stream operation failed
useful to check if file is opened successfully before performing operations on file
useful function exit() - exists program immediately. To use exit, include <cstdlib>
exit() accepts one integer as argument:
convention: 0 - normal program termination; nonzero - abnormal
Example
fin.open(”myfile.dat”); // opening file
if (fin.fail()){
cout << ”Cannot open file myfile.dat”;
exit(1); }

6. Streams as Parameters void myfunc(ifstream &myinfile);
streams can be passed as parameters
streams must be passed by reference
void myfunc(ifstream &myinfile);