What Is Cpp In Dev C++
- C++ Basics
- C++ Object Oriented
- C++ Advanced
- C++ Useful Resources
Dev C has a number limit. Dev-C is just an IDE; that statement doesn't make sense. How can I enable C to handle bigger numbers? If you code it yourself, you'd probably make a class to represent large numbers by storing sections of the data in a vector of 64-bit values, then define the operations you need to treat the vector as a single number. Oct 11, 2019 What is C used for? To start off, I wouldn’t listen to anyone who says C is only or even mostly used in legacy systems. That is flatly wrong. Legacy is a major niche, but far from the biggest or only niche. First begin by understanding who use.
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C++ pointers are easy and fun to learn. Some C++ tasks are performed more easily with pointers, and other C++ tasks, such as dynamic memory allocation, cannot be performed without them.
As you know every variable is a memory location and every memory location has its address defined which can be accessed using ampersand (&) operator which denotes an address in memory. Consider the following which will print the address of the variables defined −
When the above code is compiled and executed, it produces the following result −
What are Pointers?
A pointer is a variable whose value is the address of another variable. Like any variable or constant, you must declare a pointer before you can work with it. The general form of a pointer variable declaration is −
Here, type is the pointer's base type; it must be a valid C++ type and var-name is the name of the pointer variable. The asterisk you used to declare a pointer is the same asterisk that you use for multiplication. However, in this statement the asterisk is being used to designate a variable as a pointer. Following are the valid pointer declaration −
The actual data type of the value of all pointers, whether integer, float, character, or otherwise, is the same, a long hexadecimal number that represents a memory address. The only difference between pointers of different data types is the data type of the variable or constant that the pointer points to.
Using Pointers in C++
There are few important operations, which we will do with the pointers very frequently. (a) We define a pointer variable. (b) Assign the address of a variable to a pointer. (c) Finally access the value at the address available in the pointer variable. This is done by using unary operator * that returns the value of the variable located at the address specified by its operand. Following example makes use of these operations −
When the above code is compiled and executed, it produces result something as follows −
Pointers in C++
Pointers have many but easy concepts and they are very important to C++ programming. There are following few important pointer concepts which should be clear to a C++ programmer −
| Sr.No | Concept & Description |
|---|---|
| 1 | Null Pointers C++ supports null pointer, which is a constant with a value of zero defined in several standard libraries. |
| 2 | Pointer Arithmetic There are four arithmetic operators that can be used on pointers: ++, --, +, - |
| 3 | Pointers vs Arrays There is a close relationship between pointers and arrays. |
| 4 | Array of Pointers You can define arrays to hold a number of pointers. |
| 5 | Pointer to Pointer C++ allows you to have pointer on a pointer and so on. |
| 6 | Passing Pointers to Functions Passing an argument by reference or by address both enable the passed argument to be changed in the calling function by the called function. |
| 7 | Return Pointer from Functions /little-snitch-similar-programs-mac.html. C++ allows a function to return a pointer to local variable, static variable and dynamically allocated memory as well. |
The #define creates a macro, which is the association of an identifier or parameterized identifier with a token string. After the macro is defined, the compiler can substitute the token string for each occurrence of the identifier in the source file.
Syntax
#defineidentifiertoken-stringopt
#defineidentifier(identifieropt, .. ,identifieropt)token-stringopt
Remarks
The #define directive causes the compiler to substitute token-string for each occurrence of identifier in the source file. The identifier is replaced only when it forms a token. That is, identifier is not replaced if it appears in a comment, in a string, or as part of a longer identifier. For more information, see Tokens.
The token-string argument consists of a series of tokens, such as keywords, constants, or complete statements. One or more white-space characters must separate token-string from identifier. This white space is not considered part of the substituted text, nor is any white space that follows the last token of the text.
A #define without a token-string removes occurrences of identifier from the source file. The identifier remains defined and can be tested by using the #if defined and #ifdef directives.
The second syntax form defines a function-like macro with parameters. This form accepts an optional list of parameters that must appear in parentheses. After the macro is defined, each subsequent occurrence of identifier( identifieropt, .., identifieropt ) is replaced with a version of the token-string argument that has actual arguments substituted for formal parameters.
Formal parameter names appear in token-string to mark the locations where actual values are substituted. Each parameter name can appear multiple times in token-string, and the names can appear in any order. The number of arguments in the call must match the number of parameters in the macro definition. Liberal use of parentheses guarantees that complex actual arguments are interpreted correctly.
The formal parameters in the list are separated by commas. Each name in the list must be unique, and the list must be enclosed in parentheses. No spaces can separate identifier and the opening parenthesis. Use line concatenation — place a backslash () immediately before the newline character — for long directives on multiple source lines. The scope of a formal parameter name extends to the new line that ends token-string.
When a macro has been defined in the second syntax form, subsequent textual instances followed by an argument list indicate a macro call. The actual arguments that follows an instance of identifier in the source file are matched to the corresponding formal parameters in the macro definition. Each formal parameter in token-string that is not preceded by a stringizing (#), charizing (#@), or token-pasting (##) operator, or not followed by a ## operator, is replaced by the corresponding actual argument. Any macros in the actual argument are expanded before the directive replaces the formal parameter. Vst au alpha juno editor download. (The operators are described in Preprocessor operators.)
The following examples of macros with arguments illustrate the second form of the #define syntax:
Arguments with side effects sometimes cause macros to produce unexpected results. A given formal parameter may appear more than one time in token-string. If that formal parameter is replaced by an expression with side effects, the expression, with its side effects, may be evaluated more than one time. (See the examples under Token-Pasting Operator (##).)
The #undef directive causes an identifier's preprocessor definition to be forgotten. See The #undef Directive for more information.
If the name of the macro being defined occurs in token-string (even as a result of another macro expansion), it is not expanded.
A second #define for a macro with the same name generates a warning unless the second token sequence is identical to the first.
Microsoft Specific
Microsoft C/C++ lets you redefine a macro if the new definition is syntactically identical to the original definition. In other words, the two definitions can have different parameter names. This behavior differs from ANSI C, which requires that the two definitions be lexically identical.
For example, the following two macros are identical except for the parameter names. ANSI C does not allow such a redefinition, but Microsoft C/C++ compiles it without error.
On the other hand, the following two macros are not identical and will generate a warning in Microsoft C/C++.
END Microsoft Specific
This example illustrates the #define directive:
The first statement defines the identifier WIDTH as the integer constant 80 and defines LENGTH in terms of WIDTH and the integer constant 10. Each occurrence of LENGTH is replaced by (WIDTH + 10). In turn, each occurrence of WIDTH + 10 is replaced by the expression (80 + 10). The parentheses around WIDTH + 10 are important because they control the interpretation in statements such as the following:
After the preprocessing stage the statement becomes:
which evaluates to 1800. Without parentheses, the result is:
which evaluates to 280.
Dev C Compiler
Microsoft Specific
Defining macros and constants with the /D compiler option has the same effect as using a #define preprocessing directive at the start of your file. Up to 30 macros can be defined by using the /D option.
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END Microsoft Specific