fread():
size_t fread(void *str,size_t size,size_t num,FILE *stream);
从文件中读取size * num字节数据到str中.
fwrite():
size_t fwrite(void *str,size_t size,size_t num,FILE *stream);
把str中的数据写入文件stream内;
#include <stdio.h>
#include <string.h>
int main(){
FILE *fp = fopen("test.txt","w+");
char a[] = "fhgrffgfg";
char b[sizeof(a)];
fwrite(a,1,strlen(a),fp);
rewind(fp);
fread(b,1,strlen(a),fp);
puts(b);
//fwrite(b,1,strlen(a),stdout);
fclose(fp);
return 0;
}