C++ program to append content of one text file to another
Last Updated :
23 Nov, 2022
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Given source and destination text files. Append the content from the source file to the destination file and then display the content of the destination file.
Example :
Input : file.txt : "geeks", file2.txt : "geeks for" Output: file2.txt : "geeks for geeks"
Method 1:
Approach:
- Open file.txt in inputstream and file2.txt in outputstream with the append option, so that the previous content of the file are not deleted.
- Check if there’s an error in opening or locating a file. If yes, then throw an error message.
- If both files are found, then write content from the source file to the destination file.
- Display the content of the destination file.
Below is the implementation of the above approach:
// C++ implementation to append
// content from source file to
// destination file
#include <bits/stdc++.h>
using namespace std;
// driver code
int main()
{
fstream file;
// Input stream class to
// operate on files.
ifstream ifile("file.txt", ios::in);
// Output stream class to
// operate on files.
ofstream ofile("file2.txt", ios::out | ios::app);
// check if file exists
if (!ifile.is_open()) {
// file not found (i.e, not opened).
// Print an error message.
cout << "file not found";
}
else {
// then add more lines to
// the file if need be
ofile << ifile.rdbuf();
}
string word;
// opening file
file.open("file2.txt");
// extracting words form the file
while (file >> word) {
// displaying content of
// destination file
cout << word << " ";
}
return 0;
}
Output
file not found
Method 2: We can do the same using different functions mentioned below:
- fopen(): Returns a pointer to the object that controls the opened file stream
- fprintf(): Writes the string pointed by format to the stream
- fclose(): Closes the file associated with the stream and disassociates it.
- fgetc(): Returns the character currently pointed by the internal file position indicator of the specified stream
Approach:
- Open source file in read mode and destination file in append mode using fopen()
- check if they exist
- Iterate every character of the source file using fgetc() and print it to the destination file using fprintf() with while loop
- Close both files using fclose()
- Open destination file in read mode
- print it
- close it
Below is the implementation of the above approach:
// C++ program to Append and Read text of text files
#include <bits/stdc++.h>
using namespace std;
int main()
{
// open file in read mode to read it's content
FILE* file = fopen("file.txt", "r");
// open file in append mode to append read content
FILE* file2 = fopen("file2.txt", "a");
if (file2 == NULL) {
cout << "file not found";
return 1;
}
else if (file == NULL) {
cout << "file not found";
return 1;
}
// Read contents from file
char ch = fgetc(file);
while (ch != EOF) {
// print read content from file in file2
fprintf(file2, "%c", ch);
ch = fgetc(file);
}
fclose(file);
fclose(file2);
// open file 2 again in read mode to read the content
FILE* file3 = fopen("file2.txt", "r");
// Read contents from file
char ch2 = fgetc(file3);
while (ch2 != EOF) {
// print read content from file
printf("%c", ch2);
ch2 = fgetc(file3);
}
fclose(file3);
}
// This code is contributed by Shivesh Kumar Dwivedi
Output
file not found
