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Variables declaration in C++

Creating a variable reserves a memory location, or a space in memory for storing values. The compiler requires that you provide a data type for each variable you declare. Here some point to remember - * C++ offer a rich assortment of built-in as well as user defined data types. * Integer,

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Comments line in C++

Comments are explanatory statements that you can include in C++ code to explain what the code is doing. The compiler ignores everything that appears in the comment,so none of that information shows in the result. Single-Line Comments: Comments that require lines begin with //. You can place them on

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How to break a output line in C++

The cout operator does not insert a line break at the end of the output. One way to print two lines is to use the endl manipulator, which will put in a line break. For examle: #include<iostream.h> using namespace std; int main() { cout<<"

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Introduction to C++

C++ is a statically typed,general purpose programming language. C++ was derived C, band is largely based on it. Note: A programming language is said to used static typing when type checking is performed during compile-time as opposed to run time. Standard Libraries Standard C++ has three important components

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Difference between C and Ansi C

Main difference: C was originally developed by Dennis Ritchie at AT&T Bell Labs between 1969 and 1973. It has a free-format program source code. C is a general-purpose programming language. C is one of the oldest currently used programming languages and is one of the most

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What does the C ??!??! operator do?

??! is a trigraph that translates to |. So it says: if(a || b){ ... }else{ ... } So, what is digraphs and trigraphs? In computer programming, digraphs and trigraphs are sequences of two and three characters, respectively, that appear in source code and, according to a programming language specification, should be treated as if

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Why in C language is it the case that a[5] == 5[a]?

The C standard defines the Array Subscript Operator [] as follows: a[b] == *(a + b) Therefore a[5] will evaluate to: *(a + 5) and 5[a] will evaluate to: *(5 + a) and from elementary math we know those are equal. This is the direct artifact of arrays behaving as pointers, "

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Why isn't sizeof for a struct equal to the sum of sizeof of each member?

This is because of padding added to satisfy alignment constraints. Data structure alignment impacts both performance and correctness of programs. Here's an example using typical settings for an x86 processor (all used 32 and 64 bit modes): struct X { short s; /* 2 bytes */ /* 2 padding bytes */ int i;

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Why is one loop so much slower than two loops?

Suppose a1, b1, c1, and d1 point to heap memory and code has the following loop. const int n=100000; for(int j=0;j<n;j++){ a1[j] += b1[j]; c1[j] += d1[j]; } This loop is executed 10,000 times via another outer for loop. To speed

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Why is processing a sorted array faster than an unsorted array?

Here is a piece of Visual C++ code that seems very peculiar. For some strange reason, sorting the data miraculously makes the code almost six times faster. #include <algorithm> #include <ctime> #include <iostream> int main() { // Generate data const unsigned arraySize = 32768; int data[arraySize]

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What is the difference between #include <filename> and #include “filename”?

The difference is in the location where the preprocessor searches for the included file. For #include "filename" the preprocessor searches in the same directory as the file containing the directive. This method is normally used to include programmer-defined header files. For #include <filename> the preprocessor

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What are the differences between a pointer variable and a reference variable?

* A pointer can be re-assigned: int x = 5; int y = 6; int *p; p = &x; p = &y; *p = 10; assert(x == 5); assert(y == 10); A reference cannot, and must be assigned at initialization: int x = 5; int y = 6; int &r = x; * A pointer has

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What is the name of the "-->" operator?

Here's an example: #include <stdio.h> int main() { int x = 10; while( x --> 0 ) // x goes to 0 { printf("%d ", x); } } Answer --> is not an operator. It is in fact two separate operators, -- and >. The conditional's code decrements x,

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Quiz - Loops (for, while, do while, break, continue and goto) in C Programming

This quiz is based on this Loops in C tutorial including introduction to for loop, while loop, do while loop, break, continue statement, and goto. So, To get better score on quiz, read the tutorial first. Poll Maker

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Turbo C++ IDE Shortcuts

S.No. Shortcuts keys Action 1 F1 For Help 2. F2 Save 3. F3 Open 4. F4 Go to cursor 5. F5 Zoom 6. F6 Next 7. F7 Trace into 8. F8 Step over 9. F9 Make 10. F10 Menu 11. Alt+X Quit 12. Alt+Bksp Undo 13. Shift+