File Operation summary, file Summary

File Operation summary, file Summary
1. open the file

Function Definition: FILE * fopen (char * pname, char * mode)

Function Description: Pname is the file name, and mode is the method for opening the file (r: Read-only, w: Write only)

Return Value: If NULL is returned, opening fails.

 

2. close the file

Function Definition: Int fclose (FILE * stream)

Function Description: Stream is the pointer to the FILE object.

Return Value: If 0 is returned, it is disabled successfully.

 

3. Read one character

Function Definition: Int fgetc (FILE * stream)

Function Description: Stream is the pointer to the FILE object.

Return Value: If EOF is returned, the read operation fails.

 

4. Write a character to the file

Function Definition: Int fputc (int char, FILE * stream)

Function Description: Char is the character to be written and transmitted using an integer. stream is the pointer to the FILE object.

Return Value: If EOF is returned, the write operation fails.

 

The following describes how to copy the content of one file to another.CodeAs follows:

1 /*
  2 file operations: copy the contents of one file to another
  3 * /
  4
  5 #include <stdio.h>
  6
  7 int main () {
  8 int ch;
  9 FILE * in, * out; // pointers to input and output files
10 // File failed to open
11 if ((in = fopen ("in.txt", "r")) == NULL || (out = fopen ("out.txt", "w")) == NULL) {
12 return;
13}
14 ch = fgetc (in); // enter a character
15 while (ch! = EOF) {
16 fputc (ch, out); // write a character
17 ch = fgetc (in); // continue typing
18}
19 fclose (in); // close the file stream
20 fclose (out);
twenty one 
22 return 0;
twenty three }

 

 

5. Read a string

Function Definition: Char * fgets (char * str, int n, FILE * stream)

Function Description: Str stores the input string. n indicates reading n-1 characters. stream is the pointer to the FILE object.

Return Value: If NULL is returned, no input is returned.

 

6. Write formatted data to the file

Function Definition: Int fprintf (FILE * stream, const char * format ,...)

Function Description: Similar to the printf function, stream is the pointer to the FILE object.

Return Value: If the write operation succeeds, the total number of written characters is returned. Otherwise, a negative number is returned.

 

7. Read formatted data

Function Definition: Int fscanf (FILE * stream, const char * format ,...)

Function Description: Similar to the scanf function, stream is the pointer to the FILE object.

Return Value: If successful, this function returns the number of successful matches and assignments. If the object ends or a read error occurs, EOF is returned.

 

The functions described above can be used to format input and output files,CodeAs follows:

1 /*
  2 File operations: formatted input and output of files
  3 * /
  4
  5 #include <stdio.h>
  6
  7 int main () {
  8 int id, age; // number, age
  9 char name [10]; // name
10 FILE * in, * out; // pointers to input and output files
11 // Failed to open the file
12 if ((in = fopen ("in.txt", "r")) == NULL || (out = fopen ("out.txt", "w")) == NULL) {
13 return;
14}
15 // Enter by format
16 while (fscanf (in, "% d% s% d", & id, name, & age)! = EOF) {
17 // output as format
18 fprintf (out, "id =% 04d, name =% s, age =% 02d \ n", id, name, age);
19}
20
21 return 0;
22 }

 

8. Determine the end Of the file

Function Definition: Int feof (FILE * stream)

Function Description: Stream is the pointer to the FILE object.

Return Value: When the end object identifier associated with the stream is set, this function returns a non-zero value. Otherwise, zero is returned.

TestCodeAs follows:

1 /*
  2 File operations: feof
  3 * /
  4
  5 #include <stdio.h>
  6 #include <string.h>
  7 #include <math.h>
  8 #include <stdlib.h>
  9 #include <time.h>
10 #include <stdbool.h>
11
12 int main () {
13 char str [512];
14 FILE * in;
15 // File failed to open
16 if ((in = fopen ("in.txt", "r")) == NULL) {
17 return;
18}
19 while (! Feof (in)) {
20 fgets (str, 512, in); // enter a whole line
21 printf ("% s", str); // output
twenty two     }
twenty three 
24 return 0;
25}