Here your program will start appending content in the existing file content. Opens a text file for both reading and writing. It first truncates the file to zero length if it exists, otherwise creates a file if it does not exist. It creates the file if it does not exist. The reading will start from the beginning but writing can only be appended.
The fclose - function returns zero on success, or EOF if there is an error in closing the file. This function actually flushes any data still pending in the buffer to the file, closes the file, and releases any memory used for the file. The EOF is a constant defined in the header file stdio. There are various functions provided by C standard library to read and write a file, character by character, or in the form of a fixed length string. The function fputc writes the character value of the argument c to the output stream referenced by fp.
The only difference is that fprintf and fscanf expects a pointer to the structure FILE. After you compile and run this program, you can see a text file program. When you open the file, you can see the integer you entered. This program reads the integer present in the program. If you successfully created the file from Example 1 , running this program will get you the integer you entered. Other functions like fgetchar , fputc etc. Functions fread and fwrite are used for reading from and writing to a file on the disk respectively in case of binary files.
To write into a binary file, you need to use the fwrite function. The functions take four arguments:. We declare a structure threeNum with three numbers - n1, n2 and n3 , and define it in the main function as num. The first parameter takes the address of num and the second parameter takes the size of the structure threeNum.
Since we're only inserting one instance of num , the third parameter is 1. Function fread also take 4 arguments similar to the fwrite function as above. In this program, you read the same file program. If you have many records inside a file and need to access a record at a specific position, you need to loop through all the records before it to get the record.
This will waste a lot of memory and operation time. An easier way to get to the required data can be achieved using fseek. The first parameter stream is the pointer to the file. The second parameter is the position of the record to be found, and the third parameter specifies the location where the offset starts. This program will start reading the records from the file program. Course Index Explore Programiz. In this tutorial, you'll learn how to do file IO, text and binary, in C, using fopen , fwrite , and fread , fprintf , fscanf , fgetc and fputc.
You can think of it as the memory address of the file or the location of the file. Once you've opened a file, you can use the FILE pointer to let the compiler perform input and output functions on the file. Your users, of course, do not need to do this! In those cases, fopen will return 0, the NULL pointer. An example of fclose is fclose fp ; Reading and writing with fprintf, fscanf fputc, and fgetc To work with text input and output, you use fprintf and fscanf, both of which are similar to their friends printf and scanf except that you must pass the FILE pointer as first argument.
To create a file, use either the ofstream or fstream class, and specify the name of the file. To read from a file, use either the ifstream or fstream class, and the name of the file. Note that we also use a while loop together with the getline function which belongs to the ifstream class to read the file line by line, and to print the content of the file:.
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