File operations (read and write binary)

/***
a.txt
***/
this is a word
helloworld

/***
file.c
***/
#include<stdio.h>
#include<stdlib.h>
#include<string.h>

int main()
{
    FILE *p = fopen("./a.txt","r");
    while(!feof(p))
    {
        char buf[100] = {0};
        fscanf(p,"%s",buf);
        printf("%s\n",buf);
    }
    fclose(p);
    return 0;
}

fscanf () function, scanf uses the same. fscanf string is read from a file, scanf string is read from the keyboard. (Spaces encountered stops)

/***
a.txt
***/
23 + 45 = 
35 + 63 =
34 + 45 =

/***
file1.txt
***/
#include<stdio.h>
#include<stdlib.h>
#include<string.h>

int main()
{
    int a,b;
    FILE *p = fopen("./a.txt","r");
    while(!feof(p))
    {
        char buf[100] = {0};
        //fgets(buf,"%s",p);
        //fscanf(p,"%s",buf);
        fscanf(p,"%d + %d = ",&a,&b);
        printf("a = %d , b = %d\n",a,b);
        //printf("%s\n",buf);
    }
    fclose(p);
    return 0;
}

/***
fprintf.c
***/
#include<stdio.h>
#include<string.h>

int main()
{
    FILE *p = fopen("./b.txt","w");
    char buf[100] = "hello world";
    fprintf(p,"%s",buf);
    fclose(p);
    return 0;
}

fread () function and fwrite () functions: manipulating text files and binary files

fopen () function can only read text files

/ * ** 
fread.c 
** * / 

#include <stdio.h>
 int main () 
{ 
    the FILE * P = the fopen ( " ./a.txt " , " RB " );
     char buf [ 100 ] = { 0 }; 
fread (buf, the sizeof ( char ), . 1 , P); // The first parameter is the buffer, the second parameter is a read byte, the third // parameter indicates the number of bytes read fourth parameter file pointer indicates 
    the printf ( " buf =% S \ n- " , buf); 
    fclose (P); 
    return  0 ; 
}

/***
fread1.c
***/

#include<stdio.h>
int main()
{
    FILE *p = fopen("./a.txt","rb");

    while(!feof(p))
    {
        char buf[20] = {0};
        fread(buf,sizeof(char),sizeof(buf),p);
        printf("buf = %s\n",buf);
    }
    fclose(p);
    return 0;
}

fread () function returns a value, the return type size_t, unsigned int == "% u

/***
fread.c
***/
#include<stdio.h>
int main()
{
    FILE *p = fopen("./c.txt","rb");
    char buf[1024] = {0};
    size_t res = fread(buf,sizeof(char),sizeof(buf),p);
    printf("res = %u\n",res);
/*
    while(!feof(p))
    {
        char buf[20] = {0};
        fread(buf,sizeof(char),sizeof(buf),p);
        printf("buf = %s\n",buf);
    }
*/
    fclose(p);
    return 0;
}

/***
c.txt
***/
asd

Operating results: res = 4 (end of the file have a newline character '\ n'?);

size_t res = fread(buf,sizeof(int),sizeof(buf),p);

Run Results: res = 1;

The results read text files in the operating results and windos environment above procedure would be different.

/***
fwrite.c
***/
#include<stdio.h>

int main()
{
    FILE *p = fopen("./d.txt","wb");
    char buf[1024] = {0};
    buf[0] = 'a';
    buf[1] = 'b';
    buf[2] = 'c';
    fwrite(buf,sizeof(char),sizeof(buf),p);
    fclose(p);
    return 0;
}

Operating results: abc

File size is 1K (buf) size of the array, followed by the full file is 0.

/***
fwrite.c
***/
#include<stdio.h>

int main()
{
    FILE *p = fopen("./d.txt","w");
    int a = 0x12345678;
    fwrite(&a,sizeof(char),4,p);
    fclose(p);
    return 0;
}

File operations (read and write binary)

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