C file read/write operations

C file read/write operations
C language files

I. Basic file operations:

In C language, operations on data files are performed by file type pointers.

1. FILE type pointer definition: FILE * FILE type variable

2. Call the fopen function to open a file:

File Type pointer variable = fopen (file name, using the file opening method );

File opening methods (12 types)

File Opening Method	Meaning
Rt	Read-only opens a text file and only allows reading data
Wt	Only write to open or create a text file, only data can be written
At	Append a text file and write data at the end of the file.
Rb	Read-only open a binary file and only allow reading data
Wb	Only write to open or create a binary file, only data can be written
AB	Append a binary file and write data at the end of the file.
Rt +	Read and Write
Wt +	Read/write to open or create a text file, allowing read/write
At +	Open a text file, allow reading, or append data at the end of the file.
Rb +	Open a binary file for read and write operations.
Wb +	Read/write to open or create a binary file, allowing read and write
AB +	Open a binary file, allow reading, or append data at the end of the file.

 

3. close the file;

Fclose (File pointer)

Ii. file read/write operations

1. Character read/write functions: fgetc () and fputc ();

2. formatted read/write functions: fscanf () and fprintf ();

3. Data Block read/write functions: fread () and fwrite ();

4. String read/write functions: fgets () and fputs ();

The sample code is as follows:

 

# Include
 
  
# Include
  
   
# Include
   
    
# Include
    
     
# Define NUM 99999 // open or create a FILE * fp; int str [NUM]; void build (int a) {if (a = 1) {if (fp = fopen ("d: // 1234.txt"," w ") = NULL)/* c: \ 123.txt file */{printf ("\ nopen file error"); getchar (); exit (1) ;}} else if (a = 2) {if (fp = fopen ("d: // 1234.txt"," r ") = NULL)/* c: \ 123.txt file */{printf ("\ nopen file error"); getchar (); exit (1) ;}} else if (a = 3) {if (fp = fopen ("d: // 1234", "wb") = NULL)/* Create c: \ 123.txt file */{printf ("\ nopen file error"); getchar (); exit (1) ;}} else if (a = 4) {if (fp = fopen ("d: // 1234", "rb") = NULL)/* Create c: \ 123.txt file */{printf ("\ nopen file error"); getchar (); exit (1) ;}}// Close the file void Close () {fclose (fp) ;}// generate the written data void num () {int I; for (I = 0; I
     
      
 
      
The result is as follows: