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File Management

{C}

Programming

Programming for Problem Solving (PPS)

GTU # 3110003

USING

Prof. Nilesh Gambhava

�Computer Engineering Department,�Darshan Institute of Engineering & Technology, Rajkot

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File management is what you have, and how you want to manipulate it. - Anonymous

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Why File Management?

In real life, we want to store data permanently so that later we can retrieve it and reuse it.
A file is a collection of characters stored on a secondary storage device like hard disk, or pen drive.
There are two kinds of files that programmer deals with:

Text Files are human readable and it is a stream of plain English characters
Binary Files are computer readable, and it is a stream of processed characters and ASCII symbols

Binary File

110100110101000101101110101011101011101001101010001011011101010111010111010011

Text File

Hello, this is a text file. Whatever written here can be read easily without the help of a computer.

Prof. Nilesh Gambhava

#3110003 (PPS) – Introduction to C

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File Opening Modes

We can perform different operations on a file based on the file opening modes

Mode	Description
r	Open the file for reading only. If it exists, then the file is opened with the current contents; otherwise an error occurs.
w	Open the file for writing only. A file with specified name is created if the file does not exists. The contents are deleted, if the file already exists.
a	Open the file for appending (or adding data at the end of file) data to it. The file is opened with the current contents safe. A file with the specified name is created if the file does not exists.
r+	The existing file is opened to the beginning for both reading and writing.
w+	Same as w except both for reading and writing.
a+	Same as a except both for reading and writing.

Note: The main difference is w+ truncate the file to zero length if it exists or create a new file if it doesn't. While r+ neither deletes the content nor create a new file if it doesn't exist.

Prof. Nilesh Gambhava

#3110003 (PPS) – Introduction to C

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File Handling Functions

Basic file operation performed on a file are opening, reading, writing, and closing a file.

Syntax	Description
fp=fopen(file_name, mode);	This statement opens the file and assigns an identifier to the FILE type pointer fp. Example: fp = fopen("printfile.c","r");
fclose(filepointer);	Closes a file and release the pointer. Example: fclose(fp);
fprintf(fp, “control string”, list);	Here fp is a file pointer associated with a file. The control string contains items to be printed. The list may includes variables, constants and strings. Example: fprintf(fp, "%s %d %c", name, age, gender);

Prof. Nilesh Gambhava

#3110003 (PPS) – Introduction to C

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File Handling Functions

Syntax	Description
fscanf(fp, “control string”, list);	Here fp is a file pointer associated with a file. The control string contains items to be printed. The list may includes variables, constants and strings. Example: fscanf(fp, "%s %d", &item, &qty);
int getc( FILE *fp);	getc() returns the next character from a file referred by fp; it require the FILE pointer to tell from which file. It returns EOF for end of file or error. Example: c = getc(fp);
int putc(int c, FILE *fp);	putc() writes or appends the character c to the FILE fp. If a putc function is successful, it returns the character written, EOF if an error occurs. Example: putc(c, fp);

Prof. Nilesh Gambhava

#3110003 (PPS) – Introduction to C

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Write a C program to display content of a given file.

#include <stdio.h>

void main()

{

FILE *fp; //p is a FILE type pointer

char ch; //ch is used to store single character

fp = fopen("file1.c","r"); //open file in read mode and store file pointer in p

do { //repeat step 9 and 10 until EOF is reached

ch = getc(fp); //get character pointed by p into ch

putchar(ch); //print ch value on monitor

}while(ch != EOF); //condition to check EOF is reached or not

fclose(fp); //free up the file pointer pointed by fp

}

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Program

Prof. Nilesh Gambhava

#3110003 (PPS) – Introduction to C

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Write a C program to copy a given file.

#include <stdio.h>

void main()

{

FILE *fp1, *fp2; //p and q is a FILE type pointer

char ch; //ch is used to store temporary data

fp1 = fopen("file1.c","r"); //open file “file1.c” in read mode

fp2 = fopen("file2.c","w"); //open file “file2.c” in write mode

do { //repeat step 9 and 10 until EOF is reached

ch = getc(fp1); //get character pointed by p into ch

putc(ch, fp2); //print ch value into file, pointed by pointer q

}while(ch != EOF); //condition to check EOF is reached or not

fclose(fp1); //free up the file pointer p

fclose(fp2); //free up the file pointer q

printf("File copied successfully...");

}

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Program

Prof. Nilesh Gambhava

#3110003 (PPS) – Introduction to C

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File Positioning Functions

fseek, ftell, and rewind functions will set the file pointer to new location.
A subsequent read or write will access data from the new position.
fseek() - It is used to moves the reading control to different positions using fseek function.
ftell() - It tells the byte location of current position in file pointer.
rewind() - It moves the control to beginning of a file.

Prof. Nilesh Gambhava

#3110003 (PPS) – Introduction to C

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Write a C program to count lines, words, tabs, and characters

Lines = 22, tabs = 0, words = 152, characters = 283

#include <stdio.h>

void main()

{

FILE *p;

char ch;

int ln=0,t=0,w=0,c=0;

p = fopen("text1.txt","r");

ch = getc(p);

while (ch != EOF) {

if (ch == '\n')

ln++;

else if(ch == '\t')

t++;

else if(ch == ' ')

w++;

else

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Program

Output

c++;

ch = getc(p);

}

fclose(p);

printf("Lines = %d, tabs = %d, words = %d, characters = %d\n",ln, t, w, c);

}

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Program (contd.)

Prof. Nilesh Gambhava

#3110003 (PPS) – Introduction to C

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Thank you

✓