Server Side Programming Articles - Page 2260 of 2650

We have seen sometimes the strings are made using char s[], or sometimes char *s. So here we will see is there any difference or they are same?There are some differences. The s[] is an array, but *s is a pointer. For an example, if two declarations are like char s[20], and char *s respectively, then by using sizeof() we will get 20, and 4. The first one will be 20 as it is showing that there are 20 bytes of data. But second one is showing only 4 as this is the size of one pointer variable. For the ... Read More

The #define is preprocessor directives. So when we define some macro using #define, it replaces into the code with its value before compilation. So when the compiler does not know anything about the code, in that time also the macro values are replaced.The constant is actually a variable. By declaring this variable, it occupies memory unit. But we cannot update the value of constant type variable directly. We can change it using some pointer values.Sometimes programmer may think that using macro is better than const, as this is not taking any additional space into the memory, but for some good ... Read More

We know that we can use variable length arguments for functions in C. For that we have to use ellipsis (…). Similarly for macros, we can use variable length arguments. Here also we have to include ellipsis, The ‘__VA_ARGS__’ is used to handle variable length arguments. Concatenation operator ‘##’ is used to concatenate the variable arguments.In this example, the Macro will take variable length argument like the printf() or scanf() function. In this macro, we will print the filename, line number, and error messages. The first argument is pr. This is used to determine the priority i.e. whether it is ... Read More

Sometimes we see that there are two types of main function definition. The int main() and int main(void). So is there any difference?In C++, there is no difference. In C also both are correct. But the second one is technically better. It specifies that the function is not taking any argument. In C if some function is not specified with the arguments, then it can be called using no argument, or any number of arguments. Please check these two codes. (Remember these are in C not C++)Example#include void my_function() {    //some task } main(void) {    my_function(10, "Hello", "World"); ... Read More

In some cases we use long long in C or C++. Here we will see what is basically long long is? The long long takes twice as much memory as long. In different systems, the allocated memory space differs. On Linux environment the long takes 64-bit (8-bytes) of space, and the long long takes 128-bits (16-bytes) of space. This is used when we want to deal with some large value of integers.We can test the size of different types using this simple program.Example#include using namespace std; main() {    int a;    long b;    long long c;    cout

Here we will see how to convert bool to int equivalent in C++. Bool is a datatype in C++, and we can use true or false keyword for it. If we want to convert bool to int, we can use typecasting. Always true value will be 1, and false value will be 0.Example#include using namespace std; main() {    bool my_bool;    my_bool = true;    cout

Here we will see how to check whether a given input is integer string or a normal string. The integer string will hold all characters that are in range 0 – 9. The solution is very simple, we will simply go through each characters one by one, and check whether it is numeric or not. If it is numeric, then point to the next, otherwise return false value.Example#include using namespace std; bool isNumeric(string str) {    for (int i = 0; i < str.length(); i++)       if (isdigit(str[i]) == false)       return false; //when one ... Read More

To create high resolution timer we can use the chrono library. This library has high resolution clock. This can count in nanoseconds.In this program we will see the execution time in nanoseconds. We will take the time value at first, then another time value at the last, then find the difference to get elapsed time. Here we are using blank loop to pause the effect for sometimes.Example#include #include typedef std::chrono::high_resolution_clock Clock; main(){    auto start_time = Clock::now();    for(int i = 0; i

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 More

We can clear the console using C++ code. To do this we have to execute some system commands. In Linux systems, the POSIX is used. We can call system() function to execute system command. For clearing the console in linux, we can use “clear” command. This will be passed inside the system() function.Let us see the code to get the better idea.Example#include using namespace std; int main () {    cout