How to copy a file character-by-character in C

C is a general-purpose programming language that was developed in the 1970s. It is a compiler-based language; hence it uses C compilers to convert C code to machine instructions to be run on the CPU. It is commonly used to create programs that require low-level access to underlying system hardware.

In this Answer, we will discuss the character-by-character file copying method, in which we iterate over all the characters in the existing source file, one at a time, and add them to the destination file.

Algorithm

Below are the steps required to copy character-by-character data from one file to another.

1. We need to open the file from where we want to copy data. Let's call this file original.txt.

2. Now, we need to create and open a new file that will be used to store the data that it retrieves from the original file. We can call this file copy.txt.

Note: To open files in C we can use the function fopen().

3. Once we have opened both files, we will read each character from the file original.txt and append it to the file copy.txt. We will repeat this process till we rich the end of the original.txt file.

Note: To read data from a file, we can use the fgetc() function. To write data to a file, we can use the fputc() function.

4. Once we have copied all data from the original.txt file to the file copy.txt we will close both files.

Code application

Below, we can see a C application that shows how to implement the character-by-character copy approach to create a copy of the file named orignial.txt.

Code explanation

• Line 10: We open the file original.txt in read mode specified by the second argument r.

• Line 13: We open the file copy.txt in write mode specified by the second argument w.

• Line 16: We get the first character from the source file using the function fgetc() to check if it is empty.

• Lines 18–23: We run a loop till we have not run out of characters to read in the source file original.txt. For every character we read, we append it to the target file using the function fputc().

• Lines 26–27: After we have copied the files, we close both files using the fclose() function and display a message that prompts the user that the file was successfully copied.