Reading complete file in c

The mode of the file specifies whether to open a file for reading, writing or appending. Mind though, each mode string can include the letter b to explicitly specify binary file mode, which can be interpreted by some non-UNIX systems that treat text and binary files differently.

After the fopen returns the file pointer, we can call the fread function to read binary stream. We only use realloc , fread , ferror , and free :.

This means that in the worst case, up to chars are wasted allocated but not used , but only temporarily. At the end, the function reallocates the buffer to the optimal size.

Also, this means that we do four reallocations per megabyte of data read. The byte default in the code above is a conservative value; it works well for even old minilaptops and Raspberry Pis and most embedded devices with at least a few megabytes of RAM available for the process.

Yet, it is not so small that it slows down the operation due to many read calls, and many buffer reallocations on most systems. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. C Programming: How to read the whole file contents into a buffer [duplicate] Ask Question. Asked 9 years ago. Active 1 month ago. Viewed k times. Sunny Sunny 6, 20 20 gold badges 58 58 silver badges 96 96 bronze badges.

So, what have you tried? C programming language provides access on high level functions as well as low level OS level calls to handle file on your storage devices. This chapter will take you through the important calls for file management. You can use the fopen function to create a new file or to open an existing file. This call will initialize an object of the type FILE , which contains all the information necessary to control the stream. Opens a text file for writing.

If it does not exist, then a new file is created. Here your program will start writing content from the beginning of the file. Opens a text file for writing in appending mode. Here your program will start appending content in the existing file content. Opens a text file for both reading and writing. The algorithm presented gives the ides for writing of source codes in any high level language. The algorithm for opening and reading a text file in C has given below:.

The above source code is simple to understand and friendly due to the use of multiple comment lines. It includes a single header file: stdiio. The statement if! Finally, the opened file needs to be closed and it is done with the function fclose fp. The working mechanism of this source code is similar to above source code.

But, it uses the function fopen to open the file. After the file is opened in reading mode, the content of file. Both the source codes are well tested and error free.