File read write c

You use the operator in the same way you use it to read user input from the keyboard. Skip to content. Report a Bug. Previous Prev. Next Continue. Home Testing Expand child menu Expand. SAP Expand child menu Expand.

Web Expand child menu Expand. Must Learn Expand child menu Expand. Big Data Expand child menu Expand. 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. It returns the written character written on success otherwise EOF if there is an error. The function fputs writes the string s to the output stream referenced by fp. It returns a non-negative value on success, otherwise EOF is returned in case of any error. Try the following example.

If it is not, then before proceeding, you must create this directory on your machine. Opening a file is performed using the fopen function defined in the stdio. For reading and writing to a text file, we use the functions fprintf and fscanf.

They are just the file versions of printf and scanf. 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. Popular Tutorials Data Types in C. C for Loop. Arrays in C Programming. Pointers in C.