C++ Reference Card
C++ Data Types
Data Type Description
bool boolean (true or false)
char character ('a', 'b', etc.)
char[] character array (C-style string if null
terminated)
string C++ string (from the STL)
int integer (1, 2, -1, 1000, etc.)
long int long integer
float single precision floating point
double double precision floating point
These are the most commonly used types; this is not a
complete list.
Operators
The most commonly used operators in order of precedence:
1 ++ (post-increment), -- (post-decrement)
2 ! (not), ++ (pre-increment), -- (pre-decrement)
3 *, /, % (modulus)
4 +, -
5 <, <=, >, >=
6 == (equal-to), != (not-equal-to)
7 && (and)
8 || (or)
9 = (assignment), *=, /=, %=, +=, -=
Console Input/Output
cout << console out, printing to screen
cin >> console in, reading from keyboard
cerr << console error
Example:
cout << "Enter an integer: ";
cin >> i;
cout << "Input: " << i << endl;
File Input/Output
Example (input):
ifstream inputFile;
inputFile.open("data.txt");
inputFile >> inputVariable;
// you can also use get (char) or
// getline (entire line) in addition to >>
...
inputFile.close();
Example (output):
ofstream outFile;
outfile.open("output.txt");
outFile << outputVariable;
...
outFile.close();
Decision Statements
if Example
if (expression) if (x < y)
statement; cout << x;
if / else Example
if (expression) if (x < y)
statement; cout << x;
else else
statement; cout << y;
switch / case Example
switch(int expression) switch(choice)
{ {
case int-constant: case 0:
statement(s); cout << "Zero";
break; break;
case int-constant: case 1:
statement(s); cout << "One";
break; break;
default: default:
statement; cout << "What?";
} }
Looping
while Loop Example
while (expression) while (x < 100)
statement; cout << x++ << endl;
while (expression) while (x < 100)
{ {
statement; cout << x << endl;
statement; x++;
} }
do-while Loop Example
do do
statement; cout << x++ << endl;
while (expression); while (x < 100);
do do
{ {
statement; cout << x << endl;
statement; x++;
} }
while (expression); while (x < 100);
for Loop
for (initialization; test; update)
statement;
for (initialization; test; update)
{
statement;
statement;
}
Example
for (count = 0; count < 10; count++)
{
cout << "count equals: ";
cout << count << endl;
}
Functions
Functions return at most one value. A function that does not
return a value has a return type of void. Values needed by
a function are called parameters.
return_type function(type p1, type p2, ...)
{
statement;
statement;
...
}
Examples
int timesTwo(int v)
{
int d;
d = v * 2;
return d;
}
void printCourseNumber()
{
cout << "CSE1284" << endl;
return;
}
Passing Parameters by Value
return_type function(type p1)
Variable is passed into the function but
changes to p1 are not passed back.
Passing Parameters by Reference
return_type function(type &p1)
Variable is passed into the function and
changes to p1 are passed back.
Default Parameter Values
return_type function(type p1=val)
val is used as the value of p1 if the
function is called without a parameter.
Pointers
A pointer variable (or just pointer) is a variable that stores a
memory address. Pointers allow the indirect manipulation of
data stored in memory.
Pointers are declared using *. To set a pointer's value to the
address of another variable, use the & operator.
Example
char c = 'a';
char* cPtr;
cPtr = &c;
Use the indirection operator (*) to access or change the
value that the pointer references.
Example
// continued from example above
*cPtr = 'b';
cout << *cPtr << endl; // prints the char b
cout << c << endl; // prints the char b
Array names can be used as constant pointers, and pointers
can be used as array names.
Example
int numbers[]={10, 20, 30, 40, 50};
int* numPtr = numbers;
cout << numbers[0] << endl; // prints 10
cout << *numPtr << endl; // prints 10
cout << numbers[1] << endl; // prints 20
cout << *(numPtr + 1) << endl; // prints 20
cout << numPtr[2] << endl; // prints 30
Dynamic Memory
Allocate Memory Examples
ptr = new type; int* iPtr;
iPtr = new int;
ptr = new type[size]; int* intArray;
intArray = new int[5];
Deallocate Memory Examples
delete ptr; delete iPtr;
delete [] ptr; delete [] intArray;
Once a pointer is used to allocate the memory for an array,
array notation can be used to access the array locations.
Example
int* intArray;
intArray = new int[5];
intArray[0] = 23;
intArray[1] = 32;
Structures
Declaration Example
struct name struct Hamburger
{ {
type1 element1; int patties;
type2 element2; bool cheese;
}; };
Definition Example
name varName; Hamburger h;
name* ptrName; Hamburger* hPtr;
hPtr = &h;
Accessing Members Example
varName.element=val; h.patties = 2;
h.cheese = true;
ptrName->element=val; hPtr->patties = 1;
hPtr->cheese = false;
Structures can be used just like the built-in data types in
arrays.
