C++ Articles - Page 617 of 717

The C/C++ library function void free(void *ptr) deallocates the memory previously allocated by a call to calloc, malloc, or realloc. Following is the declaration for free() function.void free(void *ptr)This function takes a pointer ptr. This is the pointer to a memory block previously allocated with malloc, calloc or realloc to be deallocated. If a null pointer is passed as argument, no action occurs.Example#include #include #include using namespace std; int main () {    char *str;    /* Initial memory allocation */    str = (char *) malloc(15);    strcpy(str, "tutorialspoint");    cout

In C and C++, every character like 'A', 'b', '3', or '@' is stored as a number called its ASCII value. For example, 'A' is 65, and 'a' is 97. Given an integer like 97, we can convert it to its corresponding ASCII character which is 'a'. In this article, we will learn how to write a C and C++ program to convert an integer into its ASCII character. For example, we're given any integer from 0 to 127 (because the ASCII table contains 128 characters), and we need to convert it into its corresponding ASCII character: Input: 65 ... Read More

Here we will see how to pass reference of some variable in C++. Sometimes we call it as “Call by Reference”.The call by reference method of passing arguments to a function copies the reference of an argument into the formal parameter. Inside the function, the reference is used to access the actual argument used in the call. This means that changes made to the parameter affect the passed argument.To pass the value by reference, argument reference is passed to the functions just like any other value. So accordingly you need to declare the function parameters as reference types as in ... Read More

Numeric input means a value that contains only digits from 0 to 9, without any letters or special characters. In this article, we'll show you how to write a C++ program to check whether the input is numeric. Let's understand this with a few examples: //Example 1: Input: 12345 Output: Valid numeric input //Example 2: Input: 12a5 Output: Not a numeric input We will cover two common ways to check if the input is numeric or not in C++. Using std::getline with std::isdigit Check Using stringstream to Parse ... Read More

In C and C++, arrays can store multiple values of the same data type. This problem is about finding how many elements are present in a statically declared int[] array (not pointers or dynamically allocated arrays). We'll learn how to find the size of an int[] in both C and C++. Let's understand this with an example: //Example 1 input: int numbers[] = {10, 20, 30, 40, 50}; This array has 5 elements. Output: Number of elements: 5 //Example 2: Input: int values[] = {1, 2, 3}; This array has 3 elements. Output: Number of elements: 3 ... Read More

Here we will see how the copy constructors are implemented in C++. Before discussing that we should know what is the copy constructor.The copy constructor is a constructor which creates an object by initializing it with an object of the same class, which has been created previously. The copy constructor is used to −Initialize one object from another of the same type.Copy an object to pass it as an argument to a function.Copy an object to return it from a function.If a copy constructor is not defined in a class, the compiler itself defines one. If the class has pointer ... Read More

The C library function int remove(const char *filename) deletes the given filename so that it is no longer accessible.Following is the declaration for remove() function.int remove(const char *filename)This function takes the filename. This is the C string containing the name of the file to be deleted. On success, zero is returned. On error, -1 is returned, and errno is set appropriately.Example#include #include int main () {    int ret;    FILE *fp;    char filename[] = "file.txt";    fp = fopen(filename, "w");    fprintf(fp, "%s", "This is tutorialspoint.com");    fclose(fp);    ret = remove(filename);    if(ret == 0) { ... Read More

The C library function int rename(const char *old_filename, const char *new_filename) causes the filename referred to by old_filename to be changed to new_filenameFollowing is the declaration for rename() function.int rename(const char *old_filename, const char *new_filename)The parameters are old_filename − This is the C string containing the name of the file to be renamed and/or moved, new_filename − This is the C string containing the new name for the file.On success, zero is returned. On error, -1 is returned, and errno is set appropriately.Example#include int main () {    int ret;    char oldname[] = "file.txt";    char newname[] = ... Read More

Here we will see what type of operations can be performed on struct variables. Here basically one operation can be performed for struct. The operation is assignment operation. Some other operations like equality check or other are not available for stack.Example#include typedef struct { //define a structure for complex objects    int real, imag; }complex; void displayComplex(complex c){    printf("(%d + %di)", c.real, c.imag); } main() {    complex c1 = {5, 2};    complex c2 = {8, 6};    printf("Complex numbers are:");    displayComplex(c1);    displayComplex(c2); }OutputComplex numbers are: (5 + 2i) (8 + 6i)This works fine as ... Read More

Here we will see how the preprocessors are working in C or C++. Let us see what are the preprocessors.The preprocessors are the directives, which give instructions to the compiler to preprocess the information before actual compilation starts.All preprocessor directives begin with #, and only white-space characters may appear before a preprocessor directive on a line. Preprocessor directives are not C++ statements, so they do not end in a semicolon (;).You already have seen a #include directive in all the examples. This macro is used to include a header file into the source file.There are number of preprocessor directives supported ... Read More