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Reading and writing one line at a time (C-RW One Line): –A line can be read from a opened file. 

Two functions are used for reading a line:


    1. fputs(): – this function is used to write a sequence of characters in given file. It takes two arguments: First, string is to be written. Second, file pointer.

      Syntax: fputs(string, file pointer);

      2. fgets(): – This function is used to read a sequence of characters until it reaches one of the following:

        • At the new line.
        • Maximum number of characters which are specified by the programmer.
        • At the end of the file(EOF).
        It takes three arguments: First, string pointer where you want to receive string. Second, maximum number of characters to read. Third, file pointer.
        Syntax: fgets(string pointer, characters, file pointer);

        Eg:           #include

                        void main( )
                                        FILE *name;
                                        char string1[50];
                                        name = fopen(“first.txt”, “r”);
                                        while(fgets(string1, 60, name)!= NULL)
                                                        printf(“%s”, string1);
        1. Reading and writing one block at a time: – Data can be accessed in a block. Block is an array. If you want to read a block then number of elements are need to be specify.

        Function for reading/writing a block is:
        1. fread()
        2. fwrite()
        1. fread(): -This function is used to read one or more structures and it takes four arguments: First, pointer location. Second, each structure has a size and size is need to be specified here, which must be in bytes. Third, number of item to be read. Fourth, file pointer variable.
        Syntax: fread( pointer location, size, number of items, file pointer variable)
        Eg:           #include
                        void main( )
                                        FILE *file;
                                        struct student
                                                        char name[20];
                                                        int rollno;
                                        struct student std;
                                        file = fopen(“student.dat”, “r”);
                                        if(file = = NULL)
                                                        exit( );
                                                        while(fread(&std, sizeof(std), 1, file) = = 1)
                                                                        printf(“%s %d”, std.name, std.rollno);

        2. fwrite(): –This function is same as fread() it takes the same number of argument and syntax, but instead of reading elements from an array it writes element to the array.

          Syntax: fwrite(pointer location, size, number of item, pointer variable);
          We can read one word i.e. an integer value from a file also.

          Two functions are used for it:


          1. getw(): – it is used to read integer value from specified file. It takes one argument i.e. Pointer to file.

          Syntax: getw(file pointer);

          2. putw(): – it is used to write integer value on specified file and takes two arguments.

            Syntax: putw(integer value, file pointer);
            First, integer value is to b written to file. Second, file pointer.
            Now learn to Access Random files in C Programming.

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