C++ Program to Append a String in an Existing File Last Updated : 28 Jul, 2022 Summarize Comments Improve Suggest changes Share Like Article Like Report Here, we will build a C++ program to append a string in an existing file using 2 approaches i.e. Using ofstreamUsing fstreamC++ programming language offers a library called fstream consisting of different kinds of classes to handle the files while working on them. The classes present in fstream are ofstream, ifstream and fstream. The file we are considering the below examples consists of the text "Geeks for Geeks". 1. Using "ofstream"In the below code we appended a string to the "Geeks for Geeks.txt" file and printed the data in the file after appending the text. The created ofstream "ofstream of" specifies the file to be opened in write mode and "ios::app" in the open method specifies the append mode. C++ // C++ program to demonstrate appending of // a string using ofstream #include <fstream> #include <iostream> #include <string> using namespace std; int main() { ofstream of; fstream f; // opening file using ofstream of.open("Geeks for Geeks.txt", ios::app); if (!of) cout << "No such file found"; else { of << " String"; cout << "Data appended successfully\n"; of.close(); string word; // opening file using fstream f.open("Geeks for Geeks.txt"); while (f >> word) { cout << word << " "; } f.close(); } return 0; } Output: Data appended successfully Geeks for Geeks String2. Using "fstream"In the below code we appended a string to the "Geeks for Geeks.txt" file and printed the data in the file after appending the text. The created fstream "fstream f" specifies the file to be opened in reading & writing mode and "ios::app" in the open method specifies the append mode. C++ // C++ program to demonstrate appending of // a string using fstream #include <fstream> #include <string> using namespace std; int main() { fstream f; f.open("Geeks for Geeks.txt", ios::app); if (!f) cout << "No such file found"; else { f << " String_fstream"; cout << "Data appended successfully\n"; f.close(); string word; f.open("Geeks for Geeks.txt"); while (f >> word) { cout << word << " "; } f.close(); } return 0; } Output: Data appended successfully Geeks for Geeks String_fstream Comment More infoAdvertise with us A akhilvasabhaktula03 Follow Improve Article Tags : C++ Programs C++ C++ File Programs Practice Tags : CPP Similar Reads C++ Programming Language C++ is a computer programming language developed by Bjarne Stroustrup as an extension of the C language. It is known for is fast speed, low level memory management and is often taught as first programming language. 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