fopen fgetc fputc fwrite fread fgets fputs

//main.c
#include <stdio.h>
#include <string.h>int main() {FILE *fp;int ret;//打开/创建文件fp = fopen("test.txt", "wb+");if (NULL == fp) {perror("fopen fail");//perror aim to find reason of errorreturn -1; //程序退出码为-1，说r退出异常}/** putc写操作*/int i=fputc('a',fp); //写入成功返回写入字符，否则 EOFif(EOF == i){//如果提示 fputc error: Bad file descriptor，看是否读写权限有误perror("fputc error");}printf("putc = %c\n",i); //一般i=1/** getc读操作*/char c;long long pos;fseek(fp,-1,SEEK_CUR);pos= ftell(fp);       //获取位置指针距离文件开头的位置printf("after fseek pos=%ld\n",pos);while ( (c=fgetc(fp) ) != EOF){printf("%c",c);}printf("\nend of file\n");pos= ftell(fp);printf("after fgetc pos=%ld\n",pos);/** fwrite fread 读写操作-字符串*/char buf[20]="hello\nworld";ret = fwrite(buf,sizeof (char), strlen(buf),fp);printf("fwrite ret = %d\n",ret);fseek(fp,-strlen(buf),SEEK_CUR);memset(buf,0,sizeof (buf));printf("%buff= %s\n",buf);ret= fread(buf,sizeof (char),sizeof (buf),fp);printf("fread ret = %d\n",ret);pos= ftell(fp);printf("after fwrite pos=%ld\n",pos); //21/** fwrite fread 读写操作-二进制数据-整数*/
//    int num = 123456;
//    ret=fwrite(&num, sizeof(int), 1, fp);
//    printf("fwrite num ret = %d\n",ret); //1
//    fseek(fp,-sizeof(int),SEEK_CUR);
//    num=0;
//    ret = fread(&num, sizeof (int), 1, fp);
//    printf("fread num ret = %d\n",ret);  //1
//    printf("num = %d\n",num);  //123456
//    long long pos= ftell(fp);
//    printf("after fwrite pos=%ld\n",pos); //16
//
//    /*
//     * fgets puts 读写操作
//     *  fgets替换scanf: buf是字符串数组，fgets(buf,sizeof(buf),stdin);
//     *      读取文件时，将stdin换为 fp,即标准输入缓冲区->文件指针
//     *  fputs(buf,fp) fputs(buf,stdout)
//     */
//    char str[10]={0};
//    fseek(fp,-sizeof(int),SEEK_CUR);
//    while (fgets(str,sizeof (str),fp) != NULL) {
        printf("str = |%s\n",str);
//        fputs(str,stdout);
//    }
//    printf("\n%d\n", strlen(str));fclose(fp);return 0;
}