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Difference between fread and fwrite in c

It is declared in stdio. The fwrite function generally used for binary files to write the binary data into the file. On success, it returns the number of elements successfully written. On error, it returns a number of elements less than nmemb. Below example ask the name from the user and store it in the buffer.

After getting the name it writes the name in the created file using the fwrite function. The difference between fprintf and fwrite is very confusing and most of the people do not know when to use the fprintf and fwrite. Basically, both functions are used to write the data into the given output stream.

Let see an example code to understand the difference between fprintf and fwrite. In the below code, I am writing the message length and the message in the file using the fprintf and fwrite function.

In the below image, you can see the fprintf write the 22 message length in string format, so it is showing as it as I hope now you able to understand the basic difference between fprintf and fwrite. If you have still confusion, then comment in the comment box.

Below code writes the value of integer variable data into the file. The below code writes the id, first name and last name of the employee using the fwrite into the file. Skip to content. About Amlendra I am an embedded c software engineer and a corporate trainer, currently, I am working as senior software engineer in a largest Software consulting company. You might also like.

C Language. Leave a Reply Cancel reply.As we know, at the time of execution, every program comes in main memory to execute. Main memory is volatile and the data would be lost once the program is terminated.

If we need the same data again, we have to store the data in a file on the disk. A file is sequential stream of bytes ending with an end-of-file marker.

To access any file, we need to declare apointer to FILE structure and then associate it with the particular file. This pointer is referred to as file pointer. A pointer to FILE structure contains information, such as size, current file pointer position, type of file etc. The fopen function takes two arguments, the name of the file amd the mode in which the file is to be opened. Mode specify the purpose of opening the file i. When fopen function opens a file in memory, it returns a pointer to this particular file.

If fopen function can't open the file then it will return NULL. In the above example, statement 1 will open an existing in text mode and return a pointer to file. If file will not open, an appropriate message will be displayed. When the reading or writing of a file is finished, the file should be closed properly using fclose function. The fclose function does the followling tasks:. File positioning functions are used to move the pointer in a file to the desired position, without closing and re-opning the file.

NET C. File IO - Input Output. Difference between text file and binary file. Opening a file using fopen function.

difference between fread and fwrite in c

Closing a File using fclose function. Follow us. Open a text file for writing. If the file already exists, all the data will lost. If it doesnt exist, it will be created. Open a text file for appending.

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Data will be added at the end of the existing file. If file doesnt exist, it will be created. Open a binary file for writing.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. The dark mode beta is finally here.

Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I'm reading source code of the linux tool badblocks. They use the read function there. Is there a difference to the standard C fread function? I'm not counting the arguments as a difference. It is usually implemented by calling read in order to fill its buffer. More details herealthough note that this post contains some incorrect information.

As I remember it the read level APIs do not do buffering - so if you read 1 byte at a time you will have a huge perf penalty compared to doing the same thing with fread. One difference you should be aware of if you are converting code that uses one to using the other:. Calling fread is mainly used for binary file data where struct data are stored.

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The main difference between these two is the number of system calls in your application. The fread kind of standard IO library functions are optimized for system calls, rather your application making system calls. Learn more. What is the difference between read and fread? Ask Question. Asked 11 years, 1 month ago.

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Active 4 months ago. Viewed 50k times. AIB 5, 8 8 gold badges 28 28 silver badges 35 35 bronze badges. Active Oldest Votes. It makes a direct system call on UNIX. Francesco Boi 4, 4 4 gold badges 37 37 silver badges 64 64 bronze badges. Darron Darron So there are 3 buffers? Is this correct? Darron im more of a Linux guy and question was about Linux. It can differ per OS but in general one can assume that in Linux fread calls read. The last two bullet points in both the read and fread lists are nonsense.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. This function is going to be used in another function, which does a HTTP request, retrieves the request, and writes it to the local machine. That writedata function will be used for the later part. The whole operation has to be multithreadedso I was in doubt between write and fwrite.

Could someone help me outlining the differences between write and fwrite in Cso I could choose which one best fits into my problem? It's specified by the ISO C standard. It doesn't know about buffering.

The write function is a call that your program makes to the operating system and therefore it is slower than fwrite. It also lacks of buffering which makes it even slower because as the philosophy of buffering suggests: "It is faster to handle many portions of small files rather than a big one. Another noteable thing is that read and write use file descriptorsbut fread and fwrite use the FILE pointers which are actually pointers which contain file descriptors and other info about the file opened.

Learn more. Ask Question. Asked 7 years, 9 months ago.

File IO - Input Output

Active 1 year, 10 months ago. Viewed 18k times. Active Oldest Votes. Use fwrite unless you know what you're doing. Fred Foo Fred Foo k 61 61 gold badges silver badges bronze badges.By using this site, you agree to our updated Privacy Policy and our Terms of Use.

Manage your Cookies Settings. Join Now login. Ask Question. Books and documentation on C tell me fread and fwrite is "binary". What does binary mean in this? Anything to do with opening a file in binary mode? I'm also sure I've read somewhere on the net that fread and fwrite are unbuffered. True or false? I found this when googling: [ Lawrence Kirby comp. All read operations are defined to read data from the stream as if by one or more calls to fgetc and all write operations by one or more calls to fputc.

If that's true, I think it would answer the first 2 questions. Apr 12 ' Post Reply. Share this Question. Walter Roberson. More false than true. Possibly what you were looking at was an item about read and write instead of fread and fwrite. Diomidis Spinellis. Richard Heathfield. When Lawrence Kirby says something about C, you can be more sure of its accuracy than of your ability to walk in a straight line whilst sober.

How to use fwrite in c, you should know

From a quick glance at your quote, it looks perfectly correct to me. Apr 13 ' Claude Yih. Is my opinion right or wrong? Claude Yih wrote: M. The C input and output streams are typically buffered. A large chunk is read from say the disk into memory with one operation. Functions like getc, fgetc, fread, and fgets will pick data from that stream until it is empty, which will cause another transfer from the disk.By using this site, you agree to our updated Privacy Policy and our Terms of Use.

Manage your Cookies Settings. Join Now login. Ask Question. But what difference does it makes from an application programmer perspective? Can any one please explain me about this? Thank you. Cheers, Blue :. Boycott Spamazon! Nov 14 ' Post Reply. Share this Question.

difference between fread and fwrite in c

Artie Gold. From a C perspective, the difference is simple: fopenfreadfwriteetc. If you want to write portable code, use fopenetc. Jack Klein. Nowhere, because such functions are not even defined.

They do whatever the implementation says they do, and whatever that is it is not a C matter. What if the "open" function on some platform popped out the tray on the CD drive?

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What in the C standard prohibits it? Com FAQs for comp.

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Enfant Honor the memory of Grandma with this dish by utilizing her good silver soup tureen and her great grandchildren crawfish, crab or lobster will work just as well, however this dish is classically made with crawfish.

Stuffed infant heads, stuffed crawfish heads, stuffed crab or lobster shells; make patties if shell or head is not available such as with packaged crawfish, crab, or headless baby. Flour oil onions bell peppers garlic salt, pepper, etc. Set aside to drain on paper towels. Make a roux with butter, oil and flour, brown vegetables in the roux, then add chicken stock and allow to simmer for 20 minutes.

Add the patties or stuffed heads, and some loose crawfish, lobster, long piglet, or what have you.

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Cook on low for 15 minutes, then allow it to set for at least 15 minutes more. Serve over steamed rice; this dish is very impressive! Stuffed Cabbage Rolls Babies really can be found under a cabbage leaf - or one can arrange for ground beef to be found there instead. Gordon Burditt. On a particular implementation, this may be correct. In general, the line between "system calls" and "library functions" is fuzzy at best and meaningless at worst. Parse sense no. DO NOT try to mix the two sets.

The representation of an "open file handle" or whatever you call it is very different between open and fopen. Gordon L. Burditt -- Copyrightall wrongs reversed.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I've been trying to write an integer to a file open mode is w.

difference between fread and fwrite in c

So in your first case, you're writing the bytes that represent an integer to the file; if its value is "4", the four bytes will be in the non-printable ASCII range, so you won't see them in a text editor. But if you look at the size of the file, it will probably be 8, not 4 bytes. Using printf converts the integer into a series of characters, in this case "4". Using fwrite causes the actual bytes comprising the integer value to be written, in this case, the 4 bytes for the characters 'w', 'o', 'r', and 'd'.

Learn more. Asked 8 years, 9 months ago. Active 4 years, 11 months ago. Viewed 41k times. Nicolas Kaiser 1, 2 2 gold badges 13 13 silver badges 25 25 bronze badges. Shai Balassiano Shai Balassiano 2 2 gold badges 9 9 silver badges 20 20 bronze badges. Active Oldest Votes. Sign up or log in Sign up using Google.

difference between fread and fwrite in c

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