Fscanf function, fscanf

Fscanf function, fscanf
Function Definition:

int fscanf( FILE *stream, const char *format [, argument ]... );

The following is an example of csdn:

/* FSCANF.C: This program writes formatted * data to a file. It then uses fscanf to * read the various data back from the file. */#include <stdio.h>FILE *stream;void main( void ){   long l;   float fp;   char s[81];   char c;   stream = fopen( "fscanf.out", "w+" );   if( stream == NULL )      printf( "The file fscanf.out was not opened\n" );   else   {      fprintf( stream, "%s %ld %f%c", "a-string",                65000, 3.14159, 'x' );      /* Set pointer to beginning of file: */      fseek( stream, 0L, SEEK_SET );      /* Read data back from file: */      fscanf( stream, "%s", s );      fscanf( stream, "%ld", &l );      fscanf( stream, "%f", &fp );      fscanf( stream, "%c", &c );      /* Output data read: */      printf( "%s\n", s );      printf( "%ld\n", l );      printf( "%f\n", fp );      printf( "%c\n", c );      fclose( stream );   }}Outputa-string650003.141590x

The following is an example of a number of similar function operations. (It is also a general operation of files) 1 write operation function

# Include <stdio. h> main () {char * s = "That's good news");/* define the string pointer and initialize */int I = 617; /* define Integer Variables and initialize */FILE * fp;/* define FILE pointer */fp = fopne ("test. dat "," w ");/* create a text file and write only */fputs (" Your score of TOEFLis ", fp ); /* write a string of characters */fputc (':', fp) to the created file;/* write a colon to the created file: */fprintf (fp, "% d \ n", I);/* write an integer to the created file */fprintf (fp, "% s", s ); /* write a string to the created file */fclose (fp);/* close the file */}

After execution: test. dat is a file with the following content: Your score of TEFLis: 617That's good news.

2. Read operation functions

<Span style = "font-size: 14px;" >#include <stdio. h> main () {char * s, m [20]; int I; FILE * fp; fp = fopen ("test. dat "," r ");/* Open the text file read-only */fgets (s, 24, fp ); /* read 23 characters from the file */printf ("% s", s);/* output the read string */fscanf (fp, "% d ", & I);/* read integer count */printf ("% d", I);/* output read integer count */putchar (fgetc (fp )); /* read one character and output at the same time */fgets (m, 17, fp);/* read 16 characters */puts (m ); /* output the read string */fclose (fp);/* close the file */getch ();/* wait for any key */} </span>

The execution result is as follows: Your score of TOEFL is: 617
That's good news


Fscanf Function

Fscanf is similar to scanf: When data can be normally read, fscanf returns the number of data read; otherwise, EOF is returned.

# Include <stdio. h>
Const int MAX_N = 6;
Int main ()
{
Int x, I;

// Note that a new 1.txt file must be created in the same directory of the program, which contains less than MAX_N data,
// If there are only three data records: 1 2 3

FILE * myfile = fopen ("1.txt"," r ");
If (! Myfile)
{
For (I = 1; I <= MAX_N; I ++)
Fscanf (myfile, "% d", & x), printf ("% d", x );
}
Return 0;
}

Program output: 1 2 3 3 3 3, read-only from the file into the first three data. Because
Fscanf has read the end of the file and no data is readable. Therefore, the most
The next data, that is, the third data 3.

How does the C language use the fscanf () function to read all the file content?

Int [] account;
For (int I = 0 ;! Feof (file_p); ++ I)/* file_p is the File Identifier */
{
Fscanf (file_p, "% d", account [I]);
}