Software Engineers Handbook/Language Dictionary/C++
C++
[edit | edit source]C++ is an Multi-paradigmed programming language derived from C.
Type
[edit | edit source]C++ is a full, Multi-paradigmed programming language implementing the following paradigmen: generic (template metaprogramming), imperative and object-oriented (class-based)
Execution Entry Point
[edit | edit source]An executable starts with the main() method.
General Syntax
[edit | edit source]The typical statement is completed by a semi-colon. For the assignment of b to a use:
a = b;
Comments
[edit | edit source] // this is an inline comment. Everything after the // is a comment.
Block comments are specified by a starting /* and ending */ They can span multiple lines.
/*
* this is a block comment
*/
Variable Declarations
[edit | edit source]Declarations can appear anywhere in the implementation.
Declare i as an integer:
int i;
Here are two ways to declare i as an integer and give it an initial value of 0:
int i = 0;
int i(0);
Method Declaration/Implementation
[edit | edit source]Methods are declared by specifying the interface for the method. It is often declared within the scope of a class.
return_type function_name(argument_1_type arg_1_name,
argument_2_type arg_2_name,
default_argument_type default_arg_name = default_arg_value);
Method implementation repeats much of the same information
return_type class_name::function_name(argument_1_type arg_1_name,
argument_2_type arg_2_name,
default_argument_type default_arg_name)
{
// work with arg_1_name, arg_2_name, and default_arg_name
// depending on the argument types the variables are passed by
// value, reference, or are constant
// don't forget to return something of the return type
return 36;
}
IMPORTANT POINT A beginner in C/C++ might get confused about the distinction between how pointers are declared in a function prototype vs. how the function is defined. For example, if my_function does not return anything, but accepts one floating point input, its function prototype looks as follows:
void my_function(float *some_variable);
However, if the variable my_var is defined to be a pointer to a float, for example:
float *my_var;
Then the manner in which my_function is invoked is as follows:
my_function(my_var);
Beginners sometimes get confused about the fact that a "*" is used to tell the compiler in a prototype statement that a variable is a pointer, but a "*" is not syntactically used during invocation of a function that accepts a pointer as input.
Scope
[edit | edit source]Scope is defined by curly braces.
{ // this the beginning of a scope
// the scope is about to end
}
Conditional Statements
[edit | edit source]If and only if A is equal to B assign C to D, otherwise, assign E to F.
if( A == B )
{
D = C;
// more code can be added here. It is used if and only if A is equal to B
}
else
{
F = E;
// more code can be added here. It is used if and only if A is not equal to B
}
or
if( A == B )
D = C; //more lines of code are not permitted after this statement
else
F = E;
Alternatively, a switch statement can be used for multiple choice operations. This sample converts a number input to text.
switch( number_value )
{
case 37:
text = "thirty-seven";
break; // this line prevents the program from writing over this value with the
// following code
case 23:
text = "twenty-three";
break;
default: // this is used if none of the previous cases contain the value
text = "unknown number";
}
Looping Statements
[edit | edit source]This code counts from 0 to 9, adding up the contents of the array.
int i = 0;
for( int index = 0; index < 10; index = index + 1 )
{
i = array[index];
}
This code repeats until the number 4 is found. If this runs off of the end of the array, there could be a problem.
int index = 0;
while( 4 != array[index] )
{
index = index + 1;
}
This code increments the counter before the check is made, so that it starts with element 1.
int index = 0;
do
{
index = index + 1;
}
while( 4 != array[index] );
Output Statements
[edit | edit source] printf( "%s","Hello world!\n" );
or
std::cout << "Hello world!" << std::endl;
Containers
[edit | edit source]The standard template library has a variety of containers including vector, bit-set, list, map and multi-set.
Algorithms
[edit | edit source]The standard template library has a variety of algorithms including sort, remove_if, and find_if.
Garbage collection
[edit | edit source]Garbage collection is manual.
Physical Structure
[edit | edit source]Generally the interfaces are defined in header files, often *.h. The implementation files are often named *.cpp. Useful collections of classes can be compiled into libraries, often *.dll, *.a, or *.so, which can be compiled into executables (statically linked) or used on the fly (dynamically linked).
Tips
[edit | edit source]Don't confuse these two:
= // assignment
== // comparison, is equal to
Often using the one you don't want will compile, and will produce results you did not expect.
A good practice is to write; if(CONSTANT == variable) rather than if(variable == CONSTANT) since the compiler will catch; if(CONSTANT = variable) but not if(variable = CONSTANT).
Arrays start with index 0.
Web References
[edit | edit source]Books and Articles
[edit | edit source]- Bruce Eckel, Thinking in C++, Volume 1: Introduction to Standard C++ ISBN 0139798099. It has helped many people make the leap from C to C++. It is available for free online at Bruce Eckel's site.
- Nicolai M. Josuttis, The C++ Standard Library : A Tutorial and Reference ISBN 0201379260. It contains lengthy and advanced discussions on the standard template library conatiners and algorithms.
- Stanley B. Lippman, Josée Lajoie & Barbara E. Moo, C++ Primer ISBN 0321714113. This is a very thorough introduction to C++, taking nearly 1000 pages to introduce programmers to C++.
- Andrew Koenig & Barbara E. Moo, Accelerated C++ ISBN 020170353X. This is another introduction to C++, but stresses the use of the STL. It is a quite compact introduction, with a steeper learning curve better suited for those who already know another programming language.
- Scott Meyers, Effective C++ ISBN 0321334876, More Effective C++ ISBN 020163371X, Effective STL ISBN 0201749629. Meyers' series of books contain the best C++ practices, from class design to minimising compilation dependencies.
- Herbert Schildt, C++: The Complete Reference ISBN 0072226803. It contains dictionary-like listings of code syntax and usage. The structure does not make it useful to learn the language from scratch. However, it could be very useful when switching from a similar language.
- Bjarne Stroustrup, The C++ Programming Language ISBN 0201889544. Written by the creator of C++, it covers everything from the core language to the standard library. The book itself has over 1300 pages.