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Catalog

Preface ：

1. What is a document ：

1. Program files ：

2. Data files ：

3. file name ：

2. Opening and closing of files ：

1. The file pointer ：

2. Closing and opening of files ：

3. Sequential reading and writing of files ：

3. Random reading and writing of documents ：

4. Text files and binaries ：

5. Determination of the end of file reading ：

6. File buffer ：

Preface ：

When we want to save data , You can use files to store data directly on the hard disk of your computer , In this way, the data can be permanently saved

1. What is a document ：

The files on disk are files , But in programming , We generally talk about two kinds of documents ： Program files and data files

1. Program files ：

Include source files （ The suffix is .c）, Target file （windows Environment suffix is .obj）, Executable program （windows Environment suffix is .exe）.

2. Data files ：

The content of the file is not necessarily a program , It's the data that the program reads and writes when it runs , For example, the file from which the program needs to read data , Or output content file .

3. file name ：

File path + File name trunk + file extension

2. Opening and closing of files ：

1. The file pointer ：

Each used file opens a corresponding file information area in memory , It is used to store information about files , These file information is stored in a structure variable , named FILE

Define a file pointer variable ：

FILE*pf

2. Closing and opening of files ：

Opening of files ：fopen

FILE*fopen(constchar*filename,constchar*mode);

Closing of files ：fclose

intfclose(FILE*stream);

Open mode ：

3. Sequential reading and writing of files ：

1. Write a character ：

intfputc(intc,FILE*stream);

2. Read a character ：

intfgetc(FILE*stream);

3. Write a line of data ：

intfputs(constchar*string,FILE*stream);

4. Read a row of data ：

char*fgets(char*string,intn,FILE*stream);

5. Format input data ：

Format data ： Contains various data types

intfprintf(FILE*stream,constchar*format [, argument ]...);

6. Format output data ：

 intfscanf(FILE*stream,constchar*format [, argument ]... );

7. Output data in binary form ：

size_tfwrite(constvoid*buffer,size_tsize,size_tcount,FILE*stream);

take count Size is size The data of is output to the file stream in binary form

 

Because the file is written in binary form , Therefore, you cannot read the contents of the document with the naked eye  

8. Read data in binary form ：

size_tfread(void*buffer,size_tsize,size_tcount,FILE*stream);

take count Size is size The data of is read out in binary form from the file

4. Compare several sets of functions ：

scanf: Is a formatted input statement for a standardized input stream

printf: Is a formatted output statement for a standardized output stream

fscanf: It is a formatted input statement for all input streams

fprintf: Is a formatted output statement for all output streams

sscanf:

int sscanf( const char *buffer, const char *format [, argument ] ... );

Convert a string to a formatted output statement

sprintf:

int sprintf( char *buffer, const char *format [, argument] ... );

Convert the formatted input statement into the corresponding string ：

3. Random reading and writing of documents ：

1.fseek:

Locate the file pointer according to its position and offset ：

intfseek(FILE*stream,longoffset,intorigin );

2.ftell

Returns the offset of the file pointer from the starting position ：

longftell(FILE*stream);

3.rewind

Return the file pointer to the starting position ：

voidrewind(FILE*stream);

4. Text files and binaries ：

text file ： With ASCII The data stored in a file in the form of is called a text file

 

Binary ： Data is stored in binary form in memory , If it is stored directly in a file without conversion, it is a binary file

 

5. Determination of the end of file reading ：

1.feof

intfeof(FILE*stream);

Out-of-service feof The return value of is directly used to determine whether the file ends , Instead, it applies when the file reading ends , The judgment is that the read failed and ended , Or end of file

1. End of text file reading ：

fgetc Judge whether it is EOF.

fgets Determine whether the return value is NULL.

2. Binary file reading finished ：

fread Judge whether the return value is less than the actual number to be read .

1. Examples of text files ：

2. Examples of binary files ：

6. File buffer ：

Data output from memory to disk is first sent to a buffer in memory , After the buffer is filled, it is sent to the disk together . If you read data from disk to computer , Then read the data from the disk file and input it into the memory buffer （ Fill the buffer ）, And then send the data from the buffer to the program data area one by one （ Program variables, etc ）. The size of the buffer depends on C The compiler system decides .

 

summary ： So that's about C Detailed explanation of language file operation knowledge points , I hope I can help each other in the learning of programming , Promote each other , Welcome to like , Leave a comment ！！！