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Practical 2:-

AIM:-Practical-: Introduction of File in C with sample Program

File:

FILE: File is a place in the disk where a group of related data is stored.

File Operations:

Naming a file

Opening a file

Reading data from file

Writing data to a file

Closing a file

File handling functions (high level I/O functions).

fopen() creates a new file for use / open a n existing file for use

fclose() close a file which has been opened for use

getc() reads a character from a fileputc() writes a character to a file

getw() reads an integer from a file

putw() writes an integer to a file

fprintf() writes a set of data values to a file

fscanf() reads a set of data values from a file

fseek() sets the position anywhere in the file

ftell() gives the current position in the file

rewind() sets the position to the beginning of the file

Opening a file:

To store data in a file in the memory, we must specify :

1. Filename: Filename is a string of characters that make up a valid filename for the

operating systems.


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It may contains two parts, a primary name and an optional period with the extension.

Example: hello.c, input.data, test.out

2. Data structure: Data structure of a file is defined as FILE in the library of standard I/O

function definitions.FILE is defined data type.

3. Purpose: Purpose specifies the mode of opening the file

General format for declaring and opening a file :

FILE *fp; fp = fopen(filename,mode);

The first statement declares the variable fp as a pointer to the data type FILE which

contains information about the file including its name, current position of the file.

The second statement opens the file with named filename and assigns an identifier to

the fp.In the second statements modes can be one of the followings :

r ----- Open a file for reading only

w ----- Create a file for writing only

a ----- append (add) to file

r+ ---- open a file for read / write

w+ --- create a file for read / write

a+ ---- append a file for read / write

For example:

FILE *p1, *p2; p1 = fopen(data, r); p2 = fopen(results, w);

Here the file data is opened for reading and results is opened for writing.

In case, the data file does not exit , an error will occur.

In case, the results file already exits, its contents are deleted and the file is opened as

a new file.

Closing a file:

After completing the operations on the files, the file must be closed using the fclose(

) function.

Another case where we have to close a file is when we want to reopen the same file

in a different mode.

It takes the following form:

fclose(file_pointer);


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Example:

fclose(FILE *fp);

Here the argument fp is the FILE pointer.

All files are closed automatically whenever a program terminates.

INPUT/OUTPUT operations on files.

The getc and putcfunctions :

The getc is an input function and putc is an output function.

These functions can handle only one character at a time.

The getc function is used to read a character from a file which is open in read mode.

The putc function is used to write a character to a file which is open in write mode.

The general forms of getc and putcare :

putc(character, fp); getc(fp);

Example for putc :

FILE *fp1; fp1 = fopen(DATA, w); putc(d, fp1);

Here this statement writes a character contained in the character variable d to the file

DATA which is associated with FILE pointer fp1.

Example for getc :

FILE *fp2; fp2 = fopen(DATA, r); d = getc(fp2);

Here this statement reads a character from the file whose file pointer is fp2.

The file pointer moves by one character position for every operation of getc or putc.

The getc will return an end of file marker EOF when end of file has been reached.

Therefore the reading is terminated when EOF is encountered.

The getw and putwfunctions :

The getw is an input function and putw is an output function.

These functions are integer oriented functions.

These functions can handle only one integer at a time.

The getw function is used to read an integer value from a file which is open in read

mode.

The putw function is used to write an integer to a file which is open in write mode.


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The general forms of getw and putware :

putw(integer, fp); getw(fp);

Example for putw :

FILE *fp1; fp1 = fopen(DATA, w); putw(d, fp1);

Here this statement writes an integer value contained in the integer variable d to the

file DATA which is associated with FILE pointer fp1.

Example for getw :

FILE *fp2; fp2 = fopen(DATA, r); d = getw(fp2);

Here this statement reads an integer value from the file whose file pointer is fp2.

The file pointer moves by one integer value position for every operation of getw or

putw.The getw will return an end of file marker EOF when end of file has been reached.

Therefore the reading is terminated when EOF is encountered.

ftell and fseek functions on files.

ftell( ) :

ftell( ) function gives the current position in the file .


n = ftell (fp);

Here fp is a FILE pointer associated with the file.

The function ftell( ) returns a type long that gives the current file position in bytes

from the start of the file (the first byte is at position 0).

In case of an error, ftell( ) returns -1L (a type long -1).

So n will give the relative offset (in bytes) of the current position.

fseek( ) :

fseek( ) function is used to set the position anywhere in the file .


fseek(file_pointer, offset, position);

Here fp is a FILE pointer associated with the file.


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The offset specifies the number of positions to be moved from the location specified

by position.

The offset may be positive, meaning moves forwards, or negative, meaning move

backwards.

The position can take one of the following values :

VALUE MEANING 0 Starting of file 1 Current position 2 End of file

The following table shows the operations of the fseek( ) function :

STATEMENT MEANING fseek(fp,0L,0); go to the starting fseek(fp,0L,1); stay at the

current position fseek(fp,0L,2); go to the end of file fseek(fp,m,0); move to (m+1)th byte

in the file fseek(fp,m,1); go forwards by m bytes fseek(fp,-m,1); go backward by m bytes

from the current position fseek(fp,-m,2); go backward by m bytes from the end

fseek( ) function returns 0 (zero) when the operation is successful. And fseek( )

function returns -1 when an error is occurs.The offset specifies the number of positions to be moved from the location specified

by position.

Sample Program:

#include #include void main() { FILE *fp; char c; int n; clrscr();

fp=fopen("ankit.txt","w"); printf("enter file content(press enter for exit)\n\n");

while((c=getchar())!='\n') putc(c,fp); fclose(fp); fp=fopen("ankit.txt","r"); printf("\n

***** file content***\n\n"); while((c=getc(fp))!=EOF) { n=ftell(fp);

printf("\n%c\t%d",c,n); } fclose(fp); getch(); }

*************************************************************


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Practical 3:

AIM:Write a proramme to copy text from one file to another file.

#include

#include

#include

void main()

{

FILE *fp1,*fp2;

char c;

fp1=fopen("D:/a.txt","r");

fp2=fopen("D:/b.txt","w");

while((c=getc(fp1))!=EOF)

{

putc(c,fp2);

}

fclose(fp1);

fclose(fp2);

}


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OUTPUT:


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Practical 4:

AIM: Write a program to read text from user and write it into the file and also read the text

from file and display on the output terminal.

#include

#include

#include

#include

void main()

{

FILE *fp1,*fp2;char c,d,e[10],f[10];

clrscr();

int i;

fp1=fopen("D:/a.txt","w");

printf("\n enter the string");

scanf("%s",e);

for(i=0;e[i]!='\0';i++)

{ putc(e[i],fp1);

}

fclose(fp1);

fp1=fopen("d:/a.txt","r");

while((d=getc(fp1))!=EOF)

{

printf("%c",d);

}

fclose(fp1);

getch();

}


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OUTPUT:


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Practical 5:

AIM: write a program to copy from command line.

#include

#include

#include

void main(int argc,char *argv[])

{

clrscr();

FILE *fp1;

FILE *fp2;

char c;

fp1=fopen(argv[1],"r");

fp2=fopen(argv[2],"w");

getc(fp1);


{

putc(c,fp2);

}

fclose(fp1);

fclose(fp2);

getch();

}


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Practical 6:

AIM: WAP to remove comment line from the source file

#include

#include

#include

void main()

{ clrscr();

FILE *fp1;

FILE * fp2;

charc,ch;

inti;

fp1=fopen("d:/a.txt","r");

fp2=fopen("d:/b.txt","w");


{

if(c=='/')

{ ch=c;

c=getc(fp1);

if(c=='*')

{

while(1)

{

if((c=getc(fp1))=='*' &&(c=getc(fp1))=='/')

{

break;

}

}

}

else

{

putc(ch,fp2);

putc(c,fp2);

}

}

else

{

putc(c,fp2);}

}

fclose(fp1);

fclose(fp2);

getch(); }


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OUTPUT:-


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Practical 7:

Aim: Write a c program to find operator& key word.

#include

#include

#include

#include

struct operator

{

char line[50];

}s[50];

void jump(char str[]);

void main()

{

inti=0,j,b,c=0,k;

int c1,c2;

charstr[50];


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clrscr();

printf("Enter the code:");

do

{

gets(s[i].line);

}while(strcmpi (s[i++].line,"end"));

i=0;

while(strcmpi (s[i].line,"end"))

{

for(j=0,k=0;s[i].line[j]!='\0';j++,k++)

{

if(s[i].line[j]=='+'||s[i].line[j]=='-'||s[i].line[j]=='/'||s[i].line[j]=='*')

{

b=j;

c1=b+1;

c2=b-1;

if(isalpha(s[i].line[c1]) &&isalpha(s[i].line[c2]))

{

printf("\n%c",s[i].line[j]);

c++;

}

}

else if(s[i].line[j]=='(' || s[i].line[j]==' ')

{


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str[k]='\0';

jump(str);

k=-1;

}

else

{

str[k]=s[i].line[j];

}

}

i++;

}

printf("\n operator=%d",c);

getch();

}

void jump(char str[])

{

int k;

char a[10][10]={"include","main","int","float","char","if","else","for","while"};

for(k=0;k


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if(strcmp(str,a[k])==0)

{

printf("%s",str);

}

}

}

Output:


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Practical 8:

AIM :- Implementation of assembler pass-1.

# include

# include

# include

void main()

{

char opcode[10],mnemonic[3],operand[10],label[10],code[10];

intlocctr,start,length;

FILE *fp1,*fp2,*fp3,*fp4;

clrscr();fp1=fopen("input.dat","r");

fp2=fopen("symtab.dat","w");

fp3=fopen("out.dat","w");

fp4=fopen("optab.dat","r");

fscanf(fp1,"%s%s%s",label,opcode,operand);

if(strcmp(opcode,"START")==0)

{

start=atoi(operand);

locctr=start;

fprintf(fp3,"\t%s\t%s\t%s\n",label,opcode,operand);


}

else

locctr=0;

while(strcmp(opcode,"END")!=0)

{

fprintf(fp3,"%d\t",locctr);

if(strcmp(label,"**")!=0)

fprintf(fp2,"%s\t%d\n",label,locctr);

rewind(fp4);

fscanf(fp4,"%s",code);

while(strcmp(code,"END")!=0)

{

if(strcmp(opcode,code)==0)

{

locctr+=3;


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break;

}

fscanf(fp4,"%s",code);

}

if(strcmp(opcode,"WORD")==0)

locctr+=3;

else if(strcmp(opcode,"RESW")==0)

locctr+=(3*(atoi(operand)));

else if(strcmp(opcode,"RESB")==0)

locctr+=(atoi(operand));

else if(strcmp(opcode,"BYTE")==0)

++locctr;

fprintf(fp3,"%s\t%s\t%s\n",label,opcode,operand);


}

fprintf(fp3,"%d\t%s\t%s\t\%s\n",locctr,label,opcode,operand);

length=locctr-start;

printf("The length of the program is %d",length);

fclose(fp1);

fclose(fp2);

fclose(fp3);

fclose(fp4);

getch();

}

INPUT FILES

INPUT.DAT

** START 2000

** LDA FIVE

** STA ALPHA

** LDCH CHARZ

** STCH C1

ALPHA RESW 1


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FIVE WORD 5

CHARZ BYTE CZ

C1 RESB 1

** END **

OPTAB.DAT

START

LDA

STA

LDCH

STCH

END

OUTPUT FILES

OUT.DAT

** START 2000

2000 ** LDA FIVE

2003 ** STA ALPHA

2006 ** LDCH CHARZ

2009 ** STCH C1

2012 ALPHA RESW 1

2015 FIVE WORD 5

2018 CHARZ BYTE CZ

2019 C1 RESB 1

2020 ** END **

SYMTAB.DAT

ALPHA 2012

FIVE 2015

CHARZ 2018

C1 2018

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