Updating a file random access in c
In this guide, we will learn how to perform input/output(I/O) operations on a file using C programming language. If the file does not open, this will display an error message to the user. If file does not open successfully then the pointer will be assigned a NULL value, so you can write the logic like this: This code will check whether the file has opened successfully or not.function, while opening you can use any of the following mode as per the requirement.Mode “r”: It is a read only mode, which means if the file is opened in r mode, it won’t allow you to write and modify content of it. The mode that we use to read a file is “r” which is “read only mode”. How to check whether the file has opened successfully? While opening a file, you need to specify the mode.You are allowed to read, write and modify the content of file opened in “r ” mode.File Pointer points to: First character of the file.
Based on the mode selected during file opening, we are allowed to perform certain operations on the file.Mode “w ”: Same as mode “w” apart from operations, which can be performed; the file can be read, write and modified in this mode.Mode “a ”: Same as mode “a”; you can read and append the data in the file, however content modification is not allowed in this mode.We have used EOF in our program to determine the end of the file.To write the file, we must open the file in a mode that supports writing.