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Aug 20, 2010 Now the questions: 1. Where and how should I store function arguments? I'm thinking about vector but vector only stores elements of the same type while I will want to pass arguments of different types to function. Math Functions and Operators in Dev-C 2013-06-10. Marina Cespedes. In this C tutorial, I’ll be teaching you how to do math functions in C. I’m going to use the addition and subtraction operators and I’m also going to show you some other mathematical functions. Partial C/C Function List This list of functions is incomplete, but will be updated when possible to eventually fill the list to all library functions. A note about C vs. C Note that header files from the C standard library should have the form headername.h when used in a C program, and the form cheadername when used in C programs (note.
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A function is a group of statements that together perform a task. Every C++ program has at least one function, which is main(), and all the most trivial programs can define additional functions.
You can divide up your code into separate functions. How you divide up your code among different functions is up to you, but logically the division usually is such that each function performs a specific task.
A function declaration tells the compiler about a function's name, return type, and parameters. A function definition provides the actual body of the function.
The C++ standard library provides numerous built-in functions that your program can call. For example, function strcat() to concatenate two strings, function memcpy() to copy one memory location to another location and many more functions.
A function is known with various names like a method or a sub-routine or a procedure etc.
Defining a Function
The general form of a C++ function definition is as follows −
A C++ function definition consists of a function header and a function body. Here are all the parts of a function −
Return Type − A function may return a value. The return_type is the data type of the value the function returns. Some functions perform the desired operations without returning a value. In this case, the return_type is the keyword void.
Function Name − This is the actual name of the function. The function name and the parameter list together constitute the function signature.
Parameters − A parameter is like a placeholder. When a function is invoked, you pass a value to the parameter. This value is referred to as actual parameter or argument. The parameter list refers to the type, order, and number of the parameters of a function. Parameters are optional; that is, a function may contain no parameters.
Function Body − The function body contains a collection of statements that define what the function does.
Example
Following is the source code for a function called max(). This function takes two parameters num1 and num2 and return the biggest of both −
Function Declarations
A function declaration tells the compiler about a function name and how to call the function. The actual body of the function can be defined separately.
A function declaration has the following parts −
For the above defined function max(), following is the function declaration −
Parameter names are not important in function declaration only their type is required, so following is also valid declaration −
Function declaration is required when you define a function in one source file and you call that function in another file. In such case, you should declare the function at the top of the file calling the function.
Calling a Function
While creating a C++ function, you give a definition of what the function has to do. To use a function, you will have to call or invoke that function.
When a program calls a function, program control is transferred to the called function. A called function performs defined task and when it’s return statement is executed or when its function-ending closing brace is reached, it returns program control back to the main program.
To call a function, you simply need to pass the required parameters along with function name, and if function returns a value, then you can store returned value. For example −
I kept max() function along with main() function and compiled the source code. While running final executable, it would produce the following result −
Function Arguments
If a function is to use arguments, it must declare variables that accept the values of the arguments. These variables are called the formal parameters of the function.
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The formal parameters behave like other local variables inside the function and are created upon entry into the function and destroyed upon exit.
While calling a function, there are two ways that arguments can be passed to a function −
| Sr.No | Call Type & Description |
|---|---|
| 1 | Call by Value This method copies the actual value of an argument into the formal parameter of the function. In this case, changes made to the parameter inside the function have no effect on the argument. |
| 2 | Call by Pointer This method copies the address of an argument into the formal parameter. Inside the function, the address is used to access the actual argument used in the call. This means that changes made to the parameter affect the argument. |
| 3 | Call by Reference This method copies the reference of an argument into the formal parameter. Inside the function, the reference is used to access the actual argument used in the call. This means that changes made to the parameter affect the argument. |
By default, C++ uses call by value to pass arguments. In general, this means that code within a function cannot alter the arguments used to call the function and above mentioned example while calling max() function used the same method.
Default Values for Parameters
When you define a function, you can specify a default value for each of the last parameters. This value will be used if the corresponding argument is left blank when calling to the function.
This is done by using the assignment operator and assigning values for the arguments in the function definition. If a value for that parameter is not passed when the function is called, the default given value is used, but if a value is specified, this default value is ignored and the passed value is used instead. Consider the following example −
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When the above code is compiled and executed, it produces the following result −
-->This reference explains the C++ programming language as implemented in the Microsoft C++ compiler. The organization is based on The Annotated C++ Reference Manual by Margaret Ellis and Bjarne Stroustrup and on the ANSI/ISO C++ International Standard (ISO/IEC FDIS 14882). Microsoft-specific implementations of C++ language features are included.
For an overview of Modern C++ programming practices, see Welcome Back to C++.
See the following tables to quickly find a keyword or operator:
In This Section
Lexical Conventions
Fundamental lexical elements of a C++ program: tokens, comments, operators, keywords, punctuators, literals. Also, file translation, operator precedence/associativity.
Basic Concepts
Scope, linkage, program startup and termination, storage classes, and types.
Built-in typesThe fundamental types that are built into the C++ compiler and their value ranges.
Standard Conversions
Type conversions between built-in types. Also, arithmetic conversions and conversions among pointer, reference, and pointer-to-member types.
Declarations and definitionsDeclaring and defining variables, types and functions.
Operators, Precedence and Associativity
The operators in C++.
Expressions
Types of expressions, semantics of expressions, reference topics on operators, casting and casting operators, run-time type information.
Lambda Expressions
A programming technique that implicitly defines a function object class and constructs a function object of that class type.
Statements
Expression, null, compound, selection, iteration, jump, and declaration statements.
Classes and structs
Introduction to classes, structures, and unions. Also, member functions, special member functions, data members, bit fields, this pointer, nested classes.
Unions
User-defined types in which all members share the same memory location.
Derived Classes
Single and multiple inheritance, virtual functions, multiple base classes, abstract classes, scope rules. Also, the __super and __interface keywords.
Member-Access Control
Controlling access to class members: public, private, and protected keywords. Friend functions and classes.
Overloading
Overloaded operators, rules for operator overloading.
Exception Handling
C++ exception handling, structured exception handling (SEH), keywords used in writing exception handling statements.
Assertion and User-Supplied Messages#error directive, the static_assert keyword, the assert macro.
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Templates
Template specifications, function templates, class templates, typename keyword, templates vs. macros, templates and smart pointers.
Event Handling
Declaring events and event handlers.
Microsoft-Specific Modifiers
Modifiers specific to Microsoft C++. Memory addressing, calling conventions, naked functions, extended storage-class attributes (__declspec), __w64.
Inline Assembler
Using assembly language and C++ in __asm blocks.
Compiler COM Support
A reference to Microsoft-specific classes and global functions used to support COM types.
Microsoft Extensions
Microsoft extensions to C++.
Nonstandard Behavior
Information about nonstandard behavior of the Microsoft C++ compiler.
Welcome Back to C++
An overview of modern C++ programming practices for writing safe, correct and efficient programs.
Related Sections
Component Extensions for Runtime Platforms
Reference material on using the Microsoft C++ compiler to target .NET.
C/C++ Building Reference
Compiler options, linker options, and other build tools.
C/C++ Preprocessor Reference
Reference material on pragmas, preprocessor directives, predefined macros, and the preprocessor.
Visual C++ Libraries
A list of links to the reference start pages for the various Microsoft C++ libraries.