c文件操作

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

man：
r：Open text file for reading. The stream is positioned at the beginning of the file.
r+：Open for reading and writing. The stream is positioned at the beginning of the file.
w：Truncate file to zero length or create text file for writing. The stream is positioned at the beginning of the file.
w+：Open for reading and writing. The file is created if it does not exist, otherwise it is truncated. The stream is positioned at the beginning of the file.
a：Open for appending (writing at end of file). The file is created if it does not exist. The stream is positioned at the end of the file.
a+：Open for reading and appending (writing at end of file). The file is created if it does not exist. The initial file position for reading is at the beginning of the file, but output is always appended to the end of the file.
b：binary

可选组合：
rb：只读打开一个二进制文件
rb+：读写打开一个二进制文件
wb：只写打开或建立一个二进制文件
wb+：读写打开或建立一个二进制文件
ab：追加打开一个二进制文件
ab+：读写打开一个二进制文件

相关函数

fgetc 读取一个字符

int fgetc(FILE *stream);

fgets 读取一行

char *fgets(char *s, int size, FILE *stream);

fputc 写入一个字符

int fputc(int c, FILE *stream);

fputs 写入字符串

int fputs(const char *s, FILE *stream);

fread 读取nmemb次，每次size个字符

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

fwrite 写入nmemb次，每次size个字符

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

fscanf 从输入流stream中写入数据

int fscanf(FILE *stream, const char *format, ...);

fprintf 向输出流stream中写入数据

int fprintf(FILE *stream, const char *format, ...);

fdopen 文件描述符转换为文件指针

FILE *fdopen(int fd, const char *mode);

feof 文件结束符

int feof(FILE *stream);

fflush 冲洗流

int fflush(FILE *stream);

fileno 文件指针转换为文件描述符

int fileno(FILE *stream);

fseek 文件指针偏移

int fseek(FILE *stream, long offset, int whence);

ftell 得到文件位置指针

long ftell(FILE *stream);