In this section we will see what is the line spacing in C or C++. Sometimes we put some single line comment using double slash “//”. The one-line comment is basically ends when we move to the next line. But if we put back slash at the end of some single line comment, then what will be the effect?When back slash is used it continues to the next lie. So after the comment line, if there are some line after comment, it will also be ignored. Let us see an example.Example Live Demo#include using namespace std; int main () { ... Read More

Writing To write a binary file in C++ use write() method. It is used to write a given number of bytes on the given stream, starting at the position of the "put" pointer. The file is extended if the put pointer is currently at the end of the file. If this pointer points into the middle of the file, characters in the file are overwritten with the new data. If any error has occurred during writing in the file, the stream is placed in an error state. Syntax of write() method ostream& write(const char*, int); Reading To read a binary ... Read More

fwrite() and fread() is used to write to a file in C.fwrite() syntaxfwrite(const void *ptr, size_t size, size_t nmemb, FILE *stream)whereptr - A pointer to array of elements to be writtensize - Size in bytes of each element to be writtennmemb - Number of elements, each one with a size of bytesstream – A pointer to a FILE object that specifies an output streamfread() syntaxfread(void *ptr, size_t size, size_t nmemb, FILE *stream)whereptr - A pointer to a block of memory with a minimum size of size*nmemb bytes.size - Size in bytes of each element to be read.nmemb - Number of ... Read More

Let us consider the following C++ sample code to get the list of files in a directory.AlgorithmBegin    Declare a poniter dr to the DIR type.    Declare another pointer en of the dirent structure.    Call opendir() function to open all file in present directory.    Initialize dr pointer as dr = opendir(".").    If(dr)       while ((en = readdir(dr)) != NULL)          print all the file name using en->d_name.       call closedir() function to close the directory. End.Example#include #include #include using namespace std; int main(void) {    DIR ... Read More

Null pointer is a pointer which points nothing.Some uses of null pointer are:b) To initialize a pointer variable when that pointer variable isn’t assigned any valid memory address yet.b) To pass a null pointer to a function argument when we don’t want to pass any valid memory address.c) To check for null pointer before accessing any pointer variable. So that, we can perform error handling in pointer related code e.g. dereference pointer variable only if it’s not NULL.In C++ if we assign 0 in any pointer that means the pointer pointing to the NULL.SyntaxFloat *p = 0 //initializing the pointer ... Read More

A pointer is used to store the address of variables. So, when we define a pointer to pointer, the first pointer is used to store the address of the second pointer. Thus it is known as double pointers.AlgorithmBegin    Declare v of the integer datatype.       Initialize v = 76.    Declare a pointer p1 of the integer datatype.    Declare another double pointer p2 of the integer datatype.    Initialize p1 as the pointer to variable v.    Initialize p2 as the pointer to variable p1.    Print “Value of v”.       Print the value ... Read More

This is a C Program to find size of a File.AlgorithmBegin    function findfileSize()    Open a file pointer fp in read only mode.    If fp is equals to null then       Print “File not found” and return -1.    Else count the file size.       Close the file.    Put the file pointer at the beginning of the file    Declare a integer variable result and initialize it with the output of the ftell() function.    Close file pointer fp.    Return result. EndExample#include int findfileSize(char f_n[]) {    FILE* fp = fopen(f_n, ... Read More

In this section we will see what are the differences between exit() and _Exit() in C and C++. In C the exit() terminates the calling process without executing the remaining code which is present after exit() function.In C++11, one new function is present called _Exit(). So what is the feature of this function? The exit() function performs some cleaning before terminating the program. It clears the connection termination, buffer flushes etc. This _Exit() function does not clean anything. If we test using atexit() method, it will not work.Let us see two examples where at first we are using exit() function, ... Read More

It is possible to pass some values from the command line to your C programs when they are executed. These values are called command line arguments and many times they are important for your program especially when you want to control your program from outside instead of hard coding those values inside the code.The command line arguments are handled using main() function arguments where argc refers to the number of arguments passed, and argv[] is a pointer array which points to each argument passed to the program. Following is a simple example which checks if there is any argument supplied ... Read More

Actually, C programs one or two static levels of pointers are common. Triple indirection is rare. But infinite is very common. Infinite pointer indirection can be achieved with the help of a struct.struct list { struct list *next; ... } lst; lst->next->next->next->...->nextand in this way we can implement multiple pointer indirection.There is another alternative notation as shown below– *(*(..(*(*(*lst).next).next).next...).next).next