Programming Articles - Page 2569 of 3363

The only way to check if a file exist is to try to open the file for reading or writing.Here is an example −In CExample#include int main() {    /* try to open file to read */    FILE *file;    if (file = fopen("a.txt", "r")) {       fclose(file);       printf("file exists");    } else {       printf("file doesn't exist");    } }Outputfile existsIn C++Example#include #include using namespace std; int main() {    /* try to open file to read */    ifstream ifile;    ifile.open("b.txt");    if(ifile) {       cout

In C++, we can read the integer values from text files using the ifstream class that allows the user to perform input operations from the files. Here, we have filename (tp.txt) that used in the program and store some integers value. 21 61 24 05 50 11 12 21 66 55 Example to Read Integers from a Text File In this example, we created one text file to save the integers values and then access those value using file handling operation. #include #include using namespace std; int main() { // Define the maximum ... Read More

Steps to write my own header file in C −Type a code and save it as “sub.h”.Write a main program “subtraction.c” in which −include new header file.Write “sub.h” instead of All the functions in sub.h header are now ready for use.Directly call the function sub().Both “subtraction.c” and “sub.h” should be in same folder.Sub.hint sub(int m, int n) {    return(m-n); }subtraction.cExample#include #include "sub.h" void main() {    int a= 7, b= 6, res;    res = sub(a, b);    printf("Subtraction of two numbers is: %d", res); }After running ”subtraction.c” the output will be −OutputSubtraction of two numbers is: 1Read More

Here is a C++ program to read file content into isstringstream in C++.Example#include #include #include using namespace std; int main() {    ifstream is("a.txt", ios::binary );    // get length of file:    is.seekg (0, std::ios::end);    long length = is.tellg();    is.seekg (0, std::ios::beg);    // allocate memory:    char *buffer = new char [length];    // read data as a block:    is.read (buffer,length);    // create string stream of memory contents    istringstream iss( string( buffer ) );    cout

In C++, the file size determines the total number of bytes. To get the file size, we can take reference of the fstream header which contains various functions such as in_file(), seekg(), and tellg(). Example Input: The file name is tp.txt content- "Hello Tutorialspoint" Output: Size of the file is 22 bytes Example Input: The file name is testfile.txt content- "Hello Tutorialspoint" Output: File size is 27 bytes Now, we will demonstrate the C++ programs of the above two examples using file handling. Getting File Size in C++ The short form of fstream header is file stream which ... Read More

Text modeBinary modeIn text mode various character translations are performed i.e;“\r+\f” is converted into “”In binary mode, such translations are not performed.To write in the files:ofstream ofs (“file.txt”);Orofstream ofs;ofs.open(“file.txt”);to write in the files: ofstream ofs(“file.txt”, ios::binary);orofstream ofs;ofs.open(“file.txt”, ios::binary);To add text at the end of the file:Ofstream ofs(“file.txt”, ios::app);orofstream ofs;ofs.open(“file.txt”, ios::app);To add text at the end of the file:Ofstreamofs(“file.txt”, ios::app|ios::binary);or ofstream ofs;ofs.open(“file.txt”, ios::app|ios::binary);To read files:ifstream in (“file.txt”);orifstreamin ; in.open(“file.txt”);To read files: ifstream in (“file.txt”, ios::binary);orifstream in ;in.open(“file.txt”, ios::binary);Read More

The C++ function std::algorithm::lexicographical_compare() tests whether one range is lexicographically less than another or not. A lexicographical comparison is the kind of comparison generally used to sort words alphabetically in dictionaries.Declarationtemplate bool lexicographical_compare(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2);AlgorithmBegin    result = lexicographical_compare(v1.begin(), v1.end(), v2.begin(), v2.end())    if (result == true)       Print v1 is less than v2    result = lexicographical_compare(v1.begin(), v1.end(), v2.begin(), v2.end())    if (result == false)       Print v1 is not less than v2 EndExample Live Demo#include #include #include #include using namespace std; int main(void) {    //initialization ... Read More

Let us consider the following example, which uses an array of 3 integers −In CExample Live Demo#include const int MAX = 3; int main () {    int var[] = {10, 100, 200};    int i;    for (i = 0; i < MAX; i++) {       printf("Value of var[%d] = %d", i, var[i] );    }    return 0; }OutputValue of var[0] = 10 Value of var[1] = 100 Value of var[2] = 200In C++Example Live Demo#include using namespace std; const int MAX = 3; int main () {    int var[] = {10, 100, 200};    int i;    for (i = 0; i < MAX; i++) {       cout

This is a C++ program in which we generate a undirected random graph for the given edges ‘e’. This algorithm basically implements on a big network and time complexity of this algorithm is O(log(n)).AlgorithmBegin    Function GenerateRandomGraphs(), has ‘e’ as the number edges in the argument list.    Initialize i = 0    while(i < e)       edge[i][0] = rand()%N+1       edge[i][1] = rand()%N+1       Increment I;    For i = 0 to N-1       Initialize count = 0       For j = 0 to e-1         ... Read More

Searching based on locality of reference, depends upon the memory access pattern data elements are reallocated.Here linear searching method is used to search an element.AlgorithmBegin    int find(int *intarray, int n, int item)    intialize comparisons = 0    for i = 0 to n-1       Increase comparisons    if(item == intarray[i])       Print element with its index    break    if(i == n-1)       Print element not found    return -1    Print Total comparisons    For j = i till i>0       intarray[j] = intarray[j-1]       intarray[0] = ... Read More