Assignment 1 due Tonight 12:00 midnight

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Project 1 is posted, and due next Friday, by midnight:

http://www.cs.unm.edu/~storm/C++/cs151_summer2001/Assignment1.html

Variable Types

Strings

• C-String
• string -- class

C-String

• Older
• Used in C
• char * string;
• require usage of special functions, such as:
• strcpy()
• strcmp()
• strchr()
• sprintf()
• basically functions are contained in the cstring library
• strxxx()

String Class

• Can use typical operators, =, +=, +, ==, etc...
• string str;
• The string library.
• The more accepted fix for C-strings.

Input and Output

• cout
• cin
• cerr

Input and Output

• cout and cin are just variables
• cout <<, cerr <<
• output streams
• cin >>
• intput stream

So, what can you do with variables?

• Arithmetic operations
• =
• ==
• +, -
• *, /

• =
• The assignment operator
• gives a variable a value
• int y = 6;
• x = y;
• often combined with arithmetic operators
• x = y+3;
• x += 3;  == x = x+3;

What can you do with variables?

• ==
• The equality operator
• tests whether a variable has a value or not

What can you do with variables?

• +, -
• The operators add and subtract
• performs the addition operation for two values or variables
• performs the subtraction operation for two values or variables

What can you do with variables?

• *, /
• The operators multiply and divide
• perform the multiplication operation for two variables or values
• perform the division operation for two variables or values

What can you do with variables?

• more on the assignment operator (=)
• it can be combined with any arithmetic operator
• +=, -=, *=, /=
• perform the operation on the variable on the left hand side and the variable on the right hand side, and place the resulting value into the left hand side variable.
• x += 3; is the same as x = x+3;

C++ Basics

#include <string>
#include <iostream>
using namespace std;

int main() {
    <statements>
    return 0;
}
 

C++ Basics

<statements>
• take the form of something ending in a semi-colon
• special case (if, else, etc...)

C++ Basics

Statements

• int y;
• float x;
• x = 3;
• cout << "Hello World!" << endl;

C++ Basics

The puts operator: <<

• Put something into an output stream (cout, cerr)
• cout << "Hello";
• string myName = "David";

cout << myName;
• can output nearly anything

C++ Basics

The gets operator: >>

• Get something from an input stream
• can only "get" into a variable, and from an input stream
• string userInput;

cin >> userInput;
• with strings, only gets characters up to the first space, or newline
• with numbers, there must be a number there, otherwise, error.

C++  Basics

Flow of Control

• if/else
• string userInput;

cin >> userInput;
if (userInput == "David") {
    return 1;
} else {
    return 0;
}

C++ Basics

Planning your program

• Flow Charts