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Articles by Samual Sam
Page 131 of 151
How to get memory usage at runtime using C++?
We can get the memory usage like virtual memory usage or resident set size etc. at run time. To get them we can use some system libraries. This process depends on operating systems. For this example, we are using Linux operating system.So 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) { ...
Read MoreHandling large numbers in C++?
In C++, we can use large numbers by using the boost library. This C++ boost library is widely used library. This is used for different sections. It has large domain of applications. For example, using boost, we can use large number like 264 in C++.Here we will see some examples of boost library. We can use big integer datatype. We can use different datatypes like int128_t, int256_t, int1024_t etc. By using this we can get precision up to 1024 easily.At first we are multiplying two huge number using boost library.Example#include #include using namespace boost::multiprecision; using namespace std; int128_t large_product(long ...
Read MoreWhat is difference between instantiating a C++ object using new vs. without new?
In C++, we can instantiate the class object with or without using the new keyword. If the new keyword is not use, then it is like normal object. This will be stored at the stack section. This will be destroyed when the scope ends. But for the case when we want to allocate the space for the item dynamically, then we can create pointer of that class, and instantiate using new operator.In C++, the new is used to dynamically allocate memory.Example#include using namespace std; class Point { int x, y, z; public: Point(int x, ...
Read MoreHow to determine the version of the C++ standard used by the compiler?
Sometimes we need to know that, what is the current C++ standard. To get this kind of information, we can use the macro called __cplusplus. For different standards, the value of this will be like below.Standard__cplusplus outputC++ pre C++981C++98199711LC++98 + TR1This cannot be checked, this will be marked as C++98C++11201103LC++14201402LC++17201703LExample#include int main() { if (__cplusplus == 201703L) std::cout
Read MoreHow can I create directory tree using C++ in Linux?
In this section we will see how to create a directory tree using C++ code in Linux. In Linux terminal we can put some command like “mkdir –p /dir/dir1/dir2” Here –p is used to mark as parent (recursively create inner directories).In C++ code we can use some libraries of Linux system. Then we can use Linux terminal commands as string argument of the system() function. We can create directory tree like this.Example#include #include #include #include using namespace std; int main() { int status; status = system("mkdir -p TP/My_Folder/test"); // Creating a directory if ...
Read MoreHow to filter String list by starting value in Java?
Let’s first create a String list −List list = new ArrayList(); list.add("wxy"); list.add("zabc"); list.add("ddd2"); list.add("def"); list.add("ghi"); list.add("wer"); list.add("uij"); list.add("wqy");To filter String list by starting value, use filter() and startsWith() −list.stream().filter((b) -> b.startsWith("w"))The following is an example to filter string list by starting value −Exampleimport java.util.ArrayList; import java.util.List; public class Demo { public static void main(final String[] args) { List list = new ArrayList(); list.add("wxy"); list.add("zabc"); list.add("ddd2"); list.add("def"); list.add("ghi"); list.add("wer"); list.add("uij"); list.add("wqy"); ...
Read MoreHow can I filter string value with starting letter?
Let’s say the following is our String List −List list = Arrays.asList("Jonny", "David", "Tony", "Jacob", "Smith", "Bravo", "Gayle", "John");Now filter the string value with starting letter −Stream stream = list.stream().filter(name -> name.startsWith("J"));The following is an example to filter string value with starting letter −Exampleimport java.util.Arrays; import java.util.List; import java.util.stream.Collectors; import java.util.stream.Stream; public class Demo { public static void main(String[] args) { List list = Arrays.asList("Jonny", "David", "Tony", "Jacob", "Smith", "Bravo", "Gayle", "John"); System.out.println("List with elements..."); for (String res : list) { System.out.print(res+" ...
Read MoreHow to Map double to int Object with mapToInt and mapToObj in Java?
At first, we have set the stream −Stream.of(3.5, 4.7, 7.9, 8.2, 9.1, 10.5, 12.3, 15.8)Now to Map double to int Object, use mapToObj −.mapToInt(Double::intValue) .mapToObj(a -> "val" + a)The following is an example to Map double to int Object with mapToInt and mapToObj −Exampleimport java.util.stream.Stream; public class Demo { public static void main(String[] args) throws Exception { Stream.of(3.5, 4.7, 7.9, 8.2, 9.1, 10.5, 12.3, 15.8) .mapToInt(Double::intValue) .mapToObj(a -> "val" + a) .forEach(System.out::println); } }Outputval3 val4 val7 val8 val9 val10 val12 val15
Read MoreMap to add String value to each element in Java
Let’s say the following is our String List −List list = Arrays.asList("Football", "Basketball", "Hockey", "Cricket", "Fencing");Now, map to add string to each element −List str = list.stream().map(name -> "Sports " + name + " Outdoor") .collect(Collectors.toList());Above, we have added “Sports” and “Outdoor” strings to each element.The following is an example to Map and add string value to each element in Java −Exampleimport java.util.Arrays; import java.util.List; import java.util.stream.Collectors; public class Demo { public static void main(String[] args) { List list = Arrays.asList("Football", "Basketball", "Hockey", "Cricket", "Fencing"); List str = list.stream().map(name -> "Sports " ...
Read MoreHow to disable a JLabel in Java?
To disable a JLabel, use the setEnabled() method −JLabel label; label.setEnabled(false);The following is an example to disable a JLabel −package my; import java.awt.Color; import java.awt.Dimension; import java.awt.Font; import javax.swing.*; import javax.swing.border.Border; public class SwingDemo { public static void main(String args[]) { JFrame frame = new JFrame("Demo"); JLabel label; label = new JLabel("First Label", JLabel.RIGHT); label.setVerticalAlignment(JLabel.TOP); label.setFont(new Font("Verdana", Font.PLAIN, 15)); label.setPreferredSize(new Dimension(250, 100)); label.setForeground(new Color(120, 90, 40)); label.setBackground(new Color(100, 20, 70)); label.setEnabled(false); ...
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