File operations in c
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This document provides information about file operations in C programming. It discusses opening, reading from, writing to, and closing files using functions like fopen(), fread(), fwrite(), fclose(), getc(), putc(), fprintf(), fscanf(), getw(), and putw(). It gives the syntax and examples of using these functions to perform basic file input/output operations like reading and writing characters, integers, and strings to files. It also covers opening files in different modes, moving the file pointer, and checking for end of file.
![fread()
• Declaration:- fread(void *ptr, size, n, FILE *stream);
• Remarks:
fread reads a specified number of equal-sized data items from an input stream into a block.
– ptr = Points to a block into which data is read
– size = Length of each item read, in bytes
– n = Number of items read
– stream = file pointer
• Example
char a[10]={'1','2','3','4','5','6','7','8','9','a'};
FILE *fs;
fs=fopen("Project.txt","w");
fwrite(a,1,10,fs);
fclose(fs)](https://image.slidesharecdn.com/fileoperationsinc-131116021048-phpapp02/85/File-operations-in-c-16-320.jpg)
![fwrite()
• Declaration:
fwrite(const void *ptr, size, n, FILE*stream);
• Remarks:
fwrite appends a specified number of equal-sized data items to an output file.
– ptr = Pointer to any object; the data written begins at ptr
– size = Length of each item of data
– n =Number of data items to be appended
– stream = file pointer
• Example
char a[10]={'1','2','3','4','5','6','7','8','9','a'};
FILE *fs;
fs=fopen("Project.txt","w");
fwrite(a,1,10,fs);
fclose(fs);](https://image.slidesharecdn.com/fileoperationsinc-131116021048-phpapp02/85/File-operations-in-c-17-320.jpg)
File operations in c
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- 5. File Operations in c Muhammed Noufal V T [email protected] www.facebook.com/vtnoufalvt twitter.com/noufalurnappy in.linkedin.com/pub/muhammed-noufal 9744003056
- 6. File management • Data can be stored on the disk and read whenever necessary, without destroying the data • C uses a structure called FILE (defined in stdio.h) to store the attributes of a file. • FILE- Place on the disk where a group of related data is stored • C supports a number of functions that have the ability to perform basic file operations -Naming a file -Opening a file -Reading data from a file -Writing data to a file -Closing a file
- 7. Basic file operations • C provides several different file operations • fopen - open a file- specify how its opened (read/write) and type (binary/text) • fclose - close an opened file • fread - read from a file • fwrite - write to a file • fseek/fsetpos - move a file pointer to somewhere in a file. • ftell/fgetpos - tell you where the file pointer is located.
- 8. Different modes • Writing mode – if file already exists then contents are deleted, – else new file with specified name created • Appending mode – if file already exists then file opened with contents safe – else new file created • Reading mode – if file already exists then opened with contents safe – else error occurs. • Additional modes – r+ open to beginning for both reading/writing – w+ same as w except both for reading and writing – a+ same as ‘a’ except both for reading and writing
- 9. Opening a FILE • Syntax -FILE *fp; /*variable fp is pointer to type FILE*/ fp = fopen(“filename”, “mode”); /*opens file with name filename , assigns identifier to fp */ • fp – contains all information about file – Communication link between system and program • The file mode tells C how the program will use the file. • The filename indicates the system name and location for the file. • We assign the return value of fopen to our pointer variable: fp = fopen(“MYFILE.TXT”, “w”); fp = fopen(“A:MYFILE.TXT”, “w”);
- 10. Closing a FILE • When we finish with a mode, we need to close the file before ending the program or beginning another mode with that same file. • To close a file, we use fclose and the pointer variable: fclose(spData); • Example: FILE *p1; p1 = fopen(“INPUT.txt”, “r”); …….. …….. fclose(p1); • pointer can be reused after closing
- 11. Input/output operations on FILES • • • • • • • C provides several different functions for reading/writing getc() – read a character putc() – write a character fprintf() – write set of data values fscanf() – read set of data values getw() – read integer putw() – write integer
- 12. getc() & putc() • handle one character at a time like getchar() and putchar() • syntax: putc(c,fp1); – c : a character variable – fp1 : pointer to file opened with mode w • syntax: c = getc(fp2); – c : a character variable – fp2 : pointer to file opened with mode r • file pointer moves by one character position after every getc() and putc() • getc() returns end-of-file marker EOF when file end reached
- 13. Program to read/write using getc() & putc() • #include <stdio.h> main() { FILE *fp1; char c; f1= fopen(“INPUT”, “w”); while((c=getchar()) != EOF) putc(c,f1); fclose(f1); f1=fopen(“INPUT”, “r”); while((c=getc(f1))!=EOF) printf(“%c”, c); fclose(f1); } /*end main */ /* open file for writing */ /*get char from keyboard until CTL-Z*/ /*write a character to INPUT */ /* close INPUT */ /* reopen file */ /*read character from file INPUT*/ /* print character to screen */
- 14. fprintf() & fscanf • similar to scanf() and printf() • Syntax:- fprintf() fprintf (fp,"string",variables); Example: int i = 12; float x = 2.356; char ch = 's'; FILE *fp; fp=fopen(“out.txt”,”w”); fprintf (fp, "%d %f %c", i, x, ch); • Syntax:- fscanf() fscanf (fp,"string",identifiers); Example: FILE *fp; Fp=fopen(“input.txt”,”r”); int i; fscanf (fp,“%d",i); • fscanf() returns EOF when end-of file reached
- 15. getw() & putw() • handle one integer at a time • syntax: putw(i,fp1); – i : an integer variable – fp1 : pointer to file ipened with mode w • syntax: i = getw(fp2); – i : an integer variable – fp2 : pointer to file opened with mode r • file pointer moves by one integer position, data stored in binary format native to local system • getw() returns end-of-file marker EOF when file end reached
- 16. fread() • Declaration:- fread(void *ptr, size, n, FILE *stream); • Remarks: fread reads a specified number of equal-sized data items from an input stream into a block. – ptr = Points to a block into which data is read – size = Length of each item read, in bytes – n = Number of items read – stream = file pointer • Example char a[10]={'1','2','3','4','5','6','7','8','9','a'}; FILE *fs; fs=fopen("Project.txt","w"); fwrite(a,1,10,fs); fclose(fs)
- 17. fwrite() • Declaration: fwrite(const void *ptr, size, n, FILE*stream); • Remarks: fwrite appends a specified number of equal-sized data items to an output file. – ptr = Pointer to any object; the data written begins at ptr – size = Length of each item of data – n =Number of data items to be appended – stream = file pointer • Example char a[10]={'1','2','3','4','5','6','7','8','9','a'}; FILE *fs; fs=fopen("Project.txt","w"); fwrite(a,1,10,fs); fclose(fs);
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