linux的fread函数的使用

#include <stdio.h>
#include <string.h>
int main()
{

        FILE *fp = NULL;
        int nRet = 0;
        char readBuff[12];
        memset(readBuff,0,12);
        fp = fopen("mm","r");
        if(fp == NULL){
                printf("open failed !\n");
                return -1;
        }
        printf("open success \n" );

        nRet = fread(readBuff,4,2,fp);
        if(nRet <= 0){
                printf("fread failed \n");
                return -3;
        }
        printf("read success %s \n",readBuff);

        nRet = fclose(fp);
        if(nRet){
                 printf("close failed \n");
                 return -2;

        }
}