File represents a set of bytes whether a text file or a binary file.
File is used to store data in the textual or in encoded format as per as use requirement.
Modes of File
| Mode |
Description |
| r |
Opens an existing text file for reading purpose. |
| w |
Opens a text file for writing. If it does not exist, then a new file is created. Here your program will start writing content from the beginning of the file. |
| a |
Opens a text file for writing in appending mode. If it does not exist, then a new file is created. Here your program will start appending content in the existing file content. |
| r+ |
Opens a text file for both reading and writing. |
| w+ |
Opens a text file for both reading and writing. It first truncates the file to zero length if it exists, otherwise creates a file if it does not exist. |
| a+ |
Opens a text file for both reading and writing. It creates the file if it does not exist. The reading will start from the beginning but writing can only be appended. |
Opening a File:
For opening a file you will use fputs function
FILE *fopen( const char * filename, const char * mode );
Closing a File :
For closing a file you will use fclose function.
int fclose( FILE *fp );
Reading a File :
#include <stdio.h>
main() {
FILE *fp;
fp = fopen("/tmp/test.txt", "w+");
fprintf(fp, "This is testing for fprintf...\n");
fputs("This is testing for fputs...\n", fp);
fclose(fp);
}
Writing a File :
For writing a file you will use fputs function
int fputs( const char *s, FILE *fp );
Writing a File :
#include <stdio.h>
main() {
FILE *fp;
fp = fopen("/tmp/test.txt", "w+");
fprintf(fp, "This is testing for fprintf...\n");
fputs("This is testing for fputs...\n", fp);
fclose(fp);
}
Reading a File :
#include <stdio.h>
main() {
FILE *fp;
char buff[255];
fp = fopen("/tmp/test.txt", "r");
fscanf(fp, "%s", buff);
printf("1 : %s\n", buff );
fgets(buff, 255, (FILE*)fp);
printf("2: %s\n", buff );
fgets(buff, 255, (FILE*)fp);
printf("3: %s\n", buff );
fclose(fp);
}
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