c库 文件操作----fopen fread fwrite fseek fclose

#include<stdio.h>
int main(void)
{
    FILE *fp;
    char *buffer="abc";
    char read_Buffer;
    if((fp = fopen("abc.txt","w+"))==NULL)
    { 
        printf("can't open abc.txt\n");
        exit(0);
    }
    if(fwrite(buffer,sizeof(char),3,fp)!=3)
        printf("can't write abc.txt\n");
    fseek(fp,1,0);
    if(fread(&read_Buffer,sizeof(char),1,fp)!=1)
        printf("can't read  abc.txt\n")    ;
    printf("%c\n",read_Buffer);
    return 0;
}