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C++ Articles
Page 9 of 597
Is it safe to delete a void pointer in C/C++?
The void pointer is a pointer which is not associated with any data type. It points to some data location in storage means points to the address of variables. It is also called general purpose pointer. However, deleting void pointers requires careful consideration for memory safety. Is It Safe to Delete a Void Pointer in C/C++? It is not safe to delete a void pointer directly because the compiler needs to know the exact type to call the appropriate destructor and determine the correct memory size to deallocate. Deleting without proper type information can lead to undefined behavior. ...
Read MoreHow to declaring pointer variables in C/C++?
A pointer is a variable that stores the memory address of another variable. To declare pointer variables in C, we use the asterisk (*) operator before the variable name during declaration. Syntax data_type *pointer_name; Where data_type is the type of variable the pointer will point to, and pointer_name is the name of the pointer variable. Basic Pointer Declaration and Usage Here's how to declare and use pointer variables in C − #include int main() { // A normal integer variable int ...
Read MoreHow to compare pointers in C/C++?
Pointers in C can be directly compared using relational operators to check their memory addresses. This allows us to determine equality, ordering, and relative positions of pointers in memory. Syntax pointer1 == pointer2 // Equality comparison pointer1 != pointer2 // Inequality comparison pointer1 < pointer2 // Less than comparison pointer1 > pointer2 // Greater than comparison pointer1 = pointer2 // Greater than or equal Pointer Comparison in C In C, we can compare pointers using relational operators ...
Read MoreThe best way to check if a file exists using standard C/C++
In C programming, checking if a file exists is a common task that can be accomplished by attempting to open the file for reading. If the file opens successfully, it exists; otherwise, it doesn't exist. Syntax FILE *fopen(const char *filename, const char *mode); Method 1: Using fopen() Function The most straightforward approach is to use fopen() to attempt opening the file in read mode − #include int main() { FILE *file; /* Try to open file for ...
Read MoreHow to use use an array of pointers (Jagged) in C/C++?
In C programming, an array of pointers (also known as jagged arrays) allows you to store multiple pointers in a single array. This is particularly useful when working with strings of different lengths or when you need to point to different memory locations dynamically. Syntax data_type *array_name[size]; Where data_type is the type of data the pointers will point to, and size is the number of pointers the array can hold. Example 1: Array of Integer Pointers The following example demonstrates how to create an array of pointers that point to integer values − ...
Read MoreWrite a program that produces different results in C and C++
Here we will see some programs that produce different results when compiled with C and C++ compilers. These differences arise from how C and C++ handle certain language features differently. Difference 1: Character Literal Size In C, character literals are treated as int type, while in C++, they are treated as char type. This affects the result of the sizeof() operator − Example: C Compiler #include int main() { printf("The character: %c, size(%d)", 'a', sizeof('a')); return 0; } The character: a, size(4) ...
Read MoreC program that won't compile in C++
C++ is largely based on C, but it enforces stricter type checking and syntax rules. While most C programs compile in C++, some valid C code will not compile in C++ due to these stricter rules. Understanding these differences helps in writing portable code. Syntax There is no specific syntax for this concept, but rather a collection of C language features that C++ treats differently or rejects entirely. Example 1: Function Declaration Requirements In C, functions can be called before declaration (with implicit declaration), but C++ requires explicit declaration − #include int ...
Read MoreFloating Point Operations and Associativity in C, C++ and Java
In C, mathematical operations with floating point numbers do not always follow the associativity rule. This means that (a + b) + c may not equal a + (b + c) due to precision limitations and rounding errors in floating-point arithmetic. Syntax float result1 = a + (b + c); /* Right associativity */ float result2 = (a + b) + c; /* Left associativity */ Example: Floating Point Associativity Issue Here's an example demonstrating how floating point operations violate associativity − #include int ...
Read MoreUndefined Behaviour in C and C++
In C programming, undefined behavior refers to situations where the language standard does not specify what should happen. When undefined behavior occurs, the program may produce unpredictable results, crash, or appear to work correctly but fail later under different conditions. Syntax /* Undefined behavior occurs when code violates C language rules */ /* Examples: dereferencing NULL pointers, buffer overflows, etc. */ Common Examples of Undefined Behavior in C Division by Zero Using Uninitialized Variables Dereferencing NULL Pointers Signed Integer Overflow Modifying String Literals 1. Division by Zero Division by zero ...
Read MoreHow to check if a variable is NULL in C/C++?
In C, there is no special method for comparing NULL values. We can use if statements to check whether a variable is null or not. NULL is a macro that represents a null pointer constant, typically defined as (void*)0. Syntax if (pointer == NULL) { /* pointer is null */ } if (pointer != NULL) { /* pointer is not null */ } Example 1: Checking File Pointer for NULL Here, we attempt to open a file in read mode that does not exist on ...
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