c读写文件

整理一波c读写文件的API。

fopen

FILE * fopen ( const char * filename, const char * mode );

In order to open a file as a binary file, a "b"character has to be included in the mode string.

fread

size_t fread ( void * ptr, size_t size, size_t count, FILE * stream );

Reads an array of count elements, each one with a size of size bytes, from the stream and stores them in the block of memory specified by ptr.

fwrite

size_t fwrite ( const void * ptr, size_t size, size_t count, FILE * stream );

Writes an array of count elements, each one with a size of size bytes, from the block of memory pointed by ptr to the current position in the stream.

 

DEMO

#include<stdio.h>

int main()
{
    FILE *fp = fopen("test.txt", "w");
    if (!fp) {
        printf("Open file failed\n");
        return 1;
    }
    char data[] = "hello world!";
    fwrite(data, 1, sizeof(data), fp);
    fclose(fp);
    
    fp = fopen("test.txt", "r");
    if (!fp) {
        printf("Open file failed\n");
        return 1;
    }
    char buffer[64];
    fread(buffer, 1, sizeof(data), fp);
    fclose(fp);
    
    printf("buffer: %s\n", buffer);
    return 0;
}