Programming Articles - Page 2664 of 3366

The regex library has different methods and features related to regular expressions. Here we will see some regex_errors. These are also present at regex library. During executing some regular expressions, we get some errors. That errors are mentioned here.FlagsErrorserror_collateIn the Regex, the names having invalid collation.error_ctypeIn the Regex, there is an invalid character class name.error_stackNot enough memory to determine regex can be matched or not.error_spaceConvert into Finite State Machine, when memory is insufficienterror_badrepeatThe string has repeat specifier ( *?+{) that was not preceded by a valid regular expression.error_complexityThe complexity of an attempted match against a regex exceeded a pre-set levelerror_rangeContaining ... Read More

Here we will see what are the differences between qsort() in C, and sort() in C++.The C provides qsort() function, that can be used for sorting an array. The function arguments and syntax is like below.void qsort(void *base, size_t num, size_t size, int (*comparator) (const void*, const void*));This function takes the base address of that array, the number of elements of that array. Size of each item in the array, and a comparator function.The C++ provides sort() function. This is present inside C++ STL. The arguments and syntax is like below.void sort(T first, T last, Compare c);Here the order of ... Read More

We have seen falling matrix scene in different films etc. Here we will see how to write a C++ program to do like that.To solve this problem, we have to care about these steps.Define width of the matrixTwo successive characters may or may not have same amount of gap between themA certain amount of delay between printing each line to visualize the falling effect.Example#include #include #include #include #include #include const int wd = 70; //set the width of the matrix window const int flipsPerLine =5; //five flips for the boolean array 'alternate' const int sleepTime = 50; //it will take ... Read More

To always display the scroll bar in a JList, use the properties HORIZONTAL_SCROLLBAR_ALWAYS and VERTICAL_SCROLLBAR_ALWAYS:JList list = new JList(sports); JScrollPane scrollPane = new JScrollPane(list); scrollPane.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS); scrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);The following is an example to create JList and display the scroll bar:Examplepackage my; import java.awt.event.*; import java.awt.*; import javax.swing.*; class SwingDemo extends JFrame {    static JFrame frame;    static JList list;    public static void main(String[] args) {       frame = new JFrame("JList Demo");       frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);       String sports[]= {"Tennis", "Archery", "Football", "Fencing", "Cricket", "Squash", "Hockey", "Rugby"};       list = new JList(sports);       ... Read More

Here we will see three functions. These functions are Rint(), rintf() and the rintl(). These functions are used to convert floating point values into rounded format.The rint() FunctionThis function is used for rounding floating point value to integer. The syntax is like below. If the result is outside of return type, the domain error may occur. When the argument is 0 or infinity, then it will return unmodifiedfloat rint(float argument) double rint(double argument) long double rint(long double argument)Example#include #include using namespace std; main() {    double a, b, x, y;    x = 53.26;    y = 53.86; ... Read More

In this section, we will see how to use the catch block for exception handling and the type conversion in C++.At first, let us see a code, and we will see what will be the output, and how they are generating.Example#include using namespace std; int main() {    try{       throw 'a';    }    catch(int a) {       cout

Here we will see how to start some third-party application like notepad or anything using C++ program. This program is very simple, we can use command prompt command to do this task.We will pass the application name inside the system() function. This will open it accordingly.Example#include using namespace std; int main() {    cout >> "Opening Nodepad.exe" >> endl;    system("notepad.exe"); }Output

To check if the second item is selected i.e. index 1, use the method isSelectedIndex():list.isSelectedIndex(1);Above, we have set the list with string values:String sports[]= { "Squash", "Fencing", "Cricket", "Football", "Hockey", "Rugby"}; JList list = new JList(sports);The following is an example to check if the second item is selected in JList:Examplepackage my; import java.awt.event.*; import java.awt.*; import javax.swing.*; class SwingDemo extends JFrame {    static JFrame frame;    static JList list;    public static void main(String[] args) {       frame = new JFrame("JList Demo");       SwingDemo s = new SwingDemo();       JPanel panel = ... Read More

Here we will see how to check how many digits are there in an integer in C++. At first we will see the traditional rule, then a shorter method and finally another approach to find the digit count. For example, given a single integer (which can be positive, negative, or zero): //Example 1 Input: 12345 Output: 5 //Example 2 Input: -789 Output: 3 Note: The minus sign (if present) is not counted as a digit. Determining how many digits there are in an integerWe can count the number of digits in an integer using different methods ... Read More

Here we will see how to get the memory usage statistics under Linux environment using C++.We can get all of the details from “/proc/self/stat” folder. Here we are taking the virtual memory status, and the resident set size.Example#include #include #include #include #include using namespace std; void mem_usage(double& vm_usage, double& resident_set) {    vm_usage = 0.0;    resident_set = 0.0;    ifstream stat_stream("/proc/self/stat", ios_base::in); //get info from proc    directory    //create some variables to get info    string pid, comm, state, ppid, pgrp, session, tty_nr;    string tpgid, flags, minflt, cminflt, majflt, cmajflt;    string ... Read More