C programming file io array

Search for: Search. Skip to content. Text File Binary File Text files in C Text files are humanly readable which is displayed in a sequence of characters that can be easily interpreted by humans as it presented in the textual form. They can be stored in plain text. They are stored in. Thus C supports some functions to handle files and performs some operations.

It includes: opening a file reading data from a file writing data to a file naming a file closing a file File handling in C For any file handling operations first, a pointer of FILE type must be declared in C. For creating new file or opening existing file For closing a file For reading a character from file For writing a character to a file For writing set of data to a file For reading set of data from a file For reading an integer from a file For writing an integer to a file For setting the position to the desired point in a file Gives the current position in a file Sets the position to the beginning of the file.

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. Find roots of a quadratic equation. We can specify only file name or full access path of the file. This file mode can be any one of the following. When we open a file using fopen, it returns pointer to the file which is captured in file pointer of type FILE.

If the file cannot be opened or some error occurs, it returns NULL to file pointer. Hence it is always necessary to check for NULL value in file pointer after opening the file. Otherwise it will throw an error while executing the program.

It is always advisable to close the files that are opened in the program. The file that we are trying to write does not exist. Suppose there is file which has all the student details like their Name, ID, Address, phone, class, marks etc. These information needs to be read from this file into the program as input and a report for each student needs to be generated.

This can be done using various file read functions like fgetchar , fgets and fscanf. These functions read the data within the file that has been opened and being pointed by the file pointer.

This function is similar to getchar function which is used to read single input character. The file can be any file like text, excel etc. It reads only one character at a time from the file. If the file is erroreneous or it could not read the file, it returns EOF.

This function reads whole line from the opened file. That means it reads entire words in each line. This function is similar to gets , but this function reads the data from the file. This is similar to scanf function used to read the input from the standard input file. Here this function reads the data from the file that is opened. Here we need to specify the datatype of the data that we are reading.

In earlier articles we have seen that outputs are displayed on the screen. If we need to see the output again after sometime, then again we have to execute it. These outputs displayed on the screen cannot be printed too.

If we need to see the output for the same set of input again or if we need to take a print of the output, it is always better to have the output in some file. Whenever we want to see the output for which program is already executed once, we can directly open the output file and see it without re-executing the program. This function is used to write character by character to opened file. Using this function, one can write only one character at a time.

This function is similar to puts.